By ERIC GAY and ELLIOT SPAGAT

SAN ANTONIO (AP) — Forty-six people were found dead after being abandoned in a tractor-trailer in the sweltering Texas heat in the latest tragedy to claim the lives of migrants smuggled across the border from Mexico to the U.S. Sixteen people were hospitalized, including four children.

A city worker heard a cry for help from the truck on a lonely San Antonio back road shortly before 6 p.m. Monday and discovered the gruesome scene, Police Chief William McManus said. Hours later, body bags lay spread on the ground near the trailer and bodies remained inside as authorities responded to the calamity.

San Antonio Mayor Ron Nirenberg said the 46 who died had “families who were likely trying to find a better life.”

“This is nothing short of a horrific human tragedy,” Nirenberg said.

It’s among the deadliest of the tragedies that have claimed thousands of lives in recent decades as people attempt to cross the U.S. border from Mexico. Ten migrants died in 2017 after being trapped inside a truck parked at a Walmart in San Antonio. In 2003, the bodies of 19 migrants were found in a sweltering truck southeast of San Antonio.

White House press secretary Karine Jean-Pierre told reporters aboard Air Force One that President Joe Biden was “closely monitoring the absolutely horrific and heartbreaking reports” from San Antonio. Jean-Pierre pushed back against some Republican lawmakers who blamed the administration for the deaths.

“Our prayers are with those who tragically lost their lives, their loved ones as well as those still fighting for their lives. We’re also grateful for the swift work of federal, state and local first responders,” Jean-Pierre said Tuesday.

The home countries of all of the migrants and how long they were abandoned on the side of the road were not immediately known.

Among them, 22 are from Mexico, seven are from Guatemala and two are from Honduras, Roberto Velasco Álvarez, head of the North America department in Mexico’s Foreign Relations Department, said on Twitter.

“Our condolences,” he tweeted. “All responsible will be brought to justice.”

South Texas has long been the busiest area for illegal border crossings. Migrants ride in vehicles through Border Patrol checkpoints to San Antonio, the closest major city, from which point they disperse across the United States.

Bexar County Judge Nelson Wolff, the county’s top elected official, said Tuesday that authorities believe the truck appeared to come from Laredo, a border city that is more than 150 miles (241 kilometer) south.

“They had just parked it on the side of the road,” Wolff said. “Apparently had mechanical problems and left it there. The sheriff thinks it came across from Laredo.”

Officials were trying to enlist help from neighboring counties to help with the number of bodies, he said.

Other incidents have occurred long before migrants reached the U.S. border. In December, more than 50 died when a semitrailer filled with migrants rolled over on a highway in southern Mexico. In October, Mexican authorities reported finding 652 migrants packed into six trailers near the U.S. border. They were stopped at a military checkpoint.

Officers arrived to find a body on the ground outside the trailer and a partially opened gate to the trailer. Three people were taken into custody, but it was unclear if they were definitively connected with human trafficking, McManus said. The trailer was gone Tuesday morning, but access to the area where it was found remained blocked.

Of the 16 taken to hospitals with heat-related illnesses, 12 were adults and four were children, said Fire Chief Charles Hood. The patients were hot to the touch and dehydrated, and no water was found in the trailer, he said.

“They were suffering from heat stroke and exhaustion,” Hood said. “It was a refrigerated tractor-trailer, but there was no visible working AC unit on that rig.”

Those in the trailer were part of a presumed migrant smuggling attempt into the United States, and the investigation was being led by U.S. Homeland Security Investigations, McManus said.

Big rigs emerged as a popular smuggling method in the early 1990s amid a surge in U.S. border enforcement in San Diego and El Paso, Texas, which were then the busiest corridors for illegal crossings.

Before that, people paid small fees to mom-and-pop operators to get them across a largely unguarded border. As crossing became exponentially more difficult after the 2001 terror attacks in the U.S., migrants were led through more perilous terrain and paid thousands of dollars more.

Heat poses a serious danger, particularly when temperatures can rise severely inside vehicles. Weather in the San Antonio area was mostly cloudy Monday, but temperatures approached 100 degrees Fahrenheit (38 degrees Celsius).

Some advocates drew a link to the Biden administration’s border policies. Aaron Reichlin-Melnick, policy director at the American Immigration Council, wrote that he had been dreading such a tragedy for months.

“With the border shut as tightly as it is today for migrants from Mexico, Guatemala, Honduras and El Salvador, people have been pushed into more and more dangerous routes. Truck smuggling is a way up,” he wrote on Twitter.

Stephen Miller, a chief architect of former President Donald Trump’s immigration policies, said, “Human smugglers and traffickers are wicked and evil” and that the administration’s approach to border security rewards their actions.

Texas Gov. Greg Abbott, a Republican running for reelection, was blunt in a tweet about the Democratic president: “These deaths are on Biden. They are a result of his deadly open border policies.”

Migrants — largely from Mexico, Guatemala, Honduras and El Salvador — have been expelled more than 2 million times under a pandemic-era rule in effect since March 2020 that denies them a chance to seek asylum but encourages repeat attempts because there are no legal consequences for getting caught. People from other countries, notably Cuba, Nicaragua and Colombia, are subject to Title 42 authority less frequently due to higher costs of sending them home, strained diplomatic relations and other considerations.

U.S. Customs and Border Protection reported 557 deaths on the southwest border in the 12-month period ending Sept. 30, more than double the 247 deaths reported in the previous year and the highest since it began keeping track in 1998. Most are related to heat exposure.

CBP has not published a death tally for this year but said that the Border Patrol performed 14,278 “search-and-rescue missions” in a seven-month period through May, exceeding the 12,833 missions performed during the previous 12-month period and up from 5,071 the year before.

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Spagat reported from San Diego. Associated Press reporter Terry Wallace contributed from Dallas.

By KEVIN McGILL, AMY FORLITI and GEOFF MULVIHILL

NEW ORLEANS (AP) — The fall of Roe v. Wade shifted the battleground over abortion to courthouses around the country Monday, as abortion foes looked to quickly enact statewide bans and the other side sought to buy more time.

The U.S. Supreme Court’s decision Friday to end constitutional protections for abortion opened the gates for a wave of litigation from all sides.

Many of the court cases will focus on “trigger laws,” adopted in 13 states in anticipation of the ruling and designed to take effect quickly. Lawsuits could also target old anti-abortion laws that went unenforced under Roe, and cases over abortion restrictions that were put on hold awaiting the Supreme Court ruling have also started to come back into play.

“We’ll be back in court tomorrow and the next day and the next day,” Nancy Northup, president and CEO of the Center for Reproductive Rights, which argued the case that resulted in Supreme Court ruling, told reporters in a video call Friday.

On Monday, abortion rights advocates asked a Florida judge to block a new state law, which bans abortions after 15 weeks with some exceptions and is set to take effect this week. Attorneys hoping to stave off a ban on abortion in Louisiana filed a lawsuit arguing state laws are unclear on when a ban can take effect and what constitutes an exception.

The American Civil Liberties Union of Arizona and an abortion-rights group filed an emergency motion Saturday seeking to block a 2021 law that they worry can be used to halt all abortions. The Planned Parenthood Association of Utah has already challenged a trigger law with narrow exceptions.

Brigitte Amiri, deputy director of the American Civil Liberties Union’s Reproductive Freedom Project, said the organization is looking at “all options” to protect access to abortion. As of Saturday, abortion services had stopped in at least 11 states — either because of state laws or confusion over them.

But in some cases, the lawsuits may only be a play for time. Even if courts block some abortion bans or restrictions from taking hold, lawmakers in many conservative state could move quickly to address any flaws cited.

That’s likely to be the case in Louisiana. The state’s Republican attorney general, Jeff Landry, took to Twitter on Friday to say bans with “trigger” provisions passed in anticipation of the ruling were immediately in effect. The only three clinics providing abortions in the state closed that day.

The plaintiffs in the lawsuit filed Monday in state court in New Orleans — including one of those clinics — don’t deny that Louisiana can now ban abortion. Instead, they contend current laws are confusing and unconstitutionally vague, according to the legal brief.

Days before Friday’s Supreme Court decision, Gov. John Bel Edwards, an anti-abortion Democrat, signed a measure into law that supporters said would clarify and eliminate any conflicts in anti-abortion laws already in state statutes. The sweeping bill includes prison terms of up to 10 years for any doctor who performs an abortion.

Like other anti-abortion statutes already on the books, it contained trigger language saying it would take effect if Roe was overturned. The lawsuit argued that left multiple, conflicting trigger mechanisms in state law.

Attorneys behind the lawsuit also alleged state law was still unclear on whether it banned an abortion prior to a fertilized egg implanting in the uterus. And while the new law provided an exception for “medically futile” pregnancies — in cases of fetuses with fatal abnormalities — the plaintiffs noted the law gave no definition for the term, leaving it up to the state health department to develop.

That makes it impossible for doctors to know what is and is not prohibited under the law, Joanna Wright, one of the attorneys filing the Louisiana suit, said.

Challenges to other trigger laws could be made on the grounds that the conditions to impose the bans have not been met, or that it was improper for a past legislature to bind the current one to a new law. Laura Herner, a professor at Mitchell Hamline School of Law in St. Paul, Minnesota, said trigger bans or restrictions could also be challenged using equal protection arguments.

She said other challenges might call into question whether laws sufficiently and clearly allow for exceptions to protect the life or health of a pregnant woman.

Newly written bans, too, will likely face challenges. Instead of relying on a constitutional protection at the federal level, abortion rights supporters will make the case that state constitutions guarantee the right to abortion.

A judge heard arguments on that issue Monday in Florida, where attorneys sought an emergency injunction to stop a new law from taking effect Friday. The ban beyond 15 weeks has exceptions to save the pregnant woman’s life or prevent physical harm or in cases where the fetus has a fatal abnormality. The ACLU of Florida has argued it violates the state’s constitution.

Still other cases could be filed as states try to sort out whether abortion bans in place before Roe was decided — sometimes referred to as “zombie laws” — apply now that there is no federal protection for abortion.

For instance, Wisconsin passed a law in 1849 banning abortions except to save the life of the mother. Attorney General Josh Kaul, a Democrat, said he does not believe it’s enforceable. Pro-Life Wisconsin and other abortion opponents have called on lawmakers to impose a new ban.

In the meantime, Planned Parenthood of Wisconsin said it immediately suspended all abortions, though the district attorneys in the counties that include Madison and Milwaukee have both suggested that they would not enforce the ban.

In Michigan, Planned Parenthood was proactive, challenging a 1931 abortion ban ahead of the Supreme Court ruling. In May, a judge said the ban could not be enforced because it violates the state’s constitution. Abortion rights supporters are now trying to get a proposed state constitutional amendment on the ballot in November to spell out that people can make their own decisions about abortion and birth control.

Advocates and experts also expect to see court fights over state efforts to pursue legal action against people who cross state lines to seek abortions — or to protect people from such action.

Idaho, Oklahoma and Texas have adopted laws that allow people to seek bounties against those who help others get abortions. There’s a question over whether that means people can be pursued across state lines — and some states acted to prevent that.

For instance, the California Legislature, controlled by Democrats, passed a bill Thursday to shield abortion providers and volunteers in the state from civil judgments imposed by other states. In liberal Massachusetts, Gov. Charlie Baker, a Republican, signed an executive order on Friday that prohibits state agencies from assisting other states’ investigations into anyone who receives or delivers reproductive health services that are legal in Massachusetts.

“It’s going to be very confusing and have a lot of moving parts and the patients are really going to be the ones who bear the brunt of this. There’s going to be a lot of confusion about where people can access abortion,” said Amiri, of the ACLU.

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Forliti reported from Minneapolis and Mulvihill from Cherry Hill, New Jersey. Associated Press writers Anthony Izaguirre in Tallahassee, Florida; Scott Bauer in Madison, Wisconsin; Kate Brumback in Atlanta; Steve LeBlanc in Boston and Don Thompson in Sacramento, California, contributed to this report.

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For AP’s full coverage of the Supreme Court ruling on abortion, go to https://apnews.com/hub/abortion.