LOS ANGELES — Thirteen people killed in a traffic collision in a remote stretch of Southern California near the Mexican border were among 44 migrants apparently smuggled through a large breach in the border wall, the U.S. Border Patrol said on Wednesday.
The migrants were traveling in a pair of S.U.V.s that crossed from Mexico into California’s Imperial Valley before dawn on Tuesday, border officials said.
One of the vehicles, a red Chevrolet Suburban, burst into flames shortly after crossing, they said. The other, a maroon Ford Expedition crammed with 25 people, traveled about 30 miles west to the town of Holtville, Calif., where shortly after sunrise it drove through an intersection and into the path of a large tractor-trailer rig.
“Initial investigation into the origins of the vehicles indicate a potential nexus to the breach in the border wall,” said Gregory Bovino, chief of the El Centro sector of the Border Patrol, which patrols the vast agricultural region in southeastern California.
Surveillance footage reviewed by the agency showed the two vehicles traveling near a 10-foot gap in the rust-colored steel bollard fence, Mr. Bovino said.
Responding to a radio dispatch about a red Suburban engulfed in flames, border agents found 19 migrants “hiding in the brush nearby” who had illegally entered the United States in the vehicle, the Border Patrol said in a statement. All 19 people were taken into custody, it said.
The Expedition, packed with 25 people, its seats ripped out except for that of the driver and front-seat passenger, continued to travel west. The tractor-trailer slammed into its side when the S.U.V. advanced into an intersection along State Route 115, a road surrounded by farming fields.
Twelve people were pronounced dead at the scene and a 13th died in a nearby hospital. Ten of the victims have been identified as Mexican citizens, according to Mexican authorities. The passengers included both men and women, ranging in age from 15 to 53.
The Border Patrol said its agents were not pursuing the Expedition at the time of the crash. But groups that work with immigrants in the region said several fatal crashes have occurred in the area, a popular migrant-smuggling corridor, as a result of high-speed chases involving law enforcement.
A Border Patrol photograph of the area where the border fence was breached showed a section where an entire panel of 18-foot-high beams had been removed and left on the ground on the Mexican side. The fencing section was built between 2007 and 2009, according to Carlos Pitones, a spokesman for the Border Patrol in the El Centro sector.
It is common for migrants to keep watch near the barrier, scale it under the cover of darkness and await smugglers who charge thousands of dollars to ferry them to cities across the United States.
Border Patrol officials said that the breach where the S.U.V.s apparently crossed was not the only place where illegal crossings have been documented, and that agents were “actively working border incursions to the east and west of where the breach occurred.”
A higher and deeper barrier, with 30-foot-high beams, was erected around Calexico, Calif., the main border town in the Imperial Valley, when President Donald J. Trump was in office.
About half of the El Centro wall section, which stretches 70 miles through rugged mountainous terrain and sand dunes, is made up of the Trump-era barrier. But that portion mainly straddles the border west of Calexico, heading toward San Diego. The older, less robust section, where the two S.U.V.s apparently crossed, dominates the eastern side toward Yuma, Ariz.
The crash occurred early Tuesday on the outskirts of Holtville, which calls itself the “carrot capital of the world.” The impact ejected many of the passengers from the vehicle, the police said.
Officer Arturo Platero of the California Highway Patrol said the driver of the Expedition, who was killed, was from the Mexican city of Mexicali, about 20 miles south of Holtville. The tractor-trailer’s driver, who was hospitalized with moderate injuries, is from El Centro, the biggest city in the area.
Several victims who experienced severe trauma were transferred to hospitals in San Diego and Palm Springs on Tuesday.
The authorities did not provide details about the other victims, but said they were working with Mexican consular officials to try to identify passengers.
“Going on 13 years, this is one of the biggest traffic collisions I have been a part of,” Officer Platero said. “We get crashes often but with this many occupants and so many casualties it is unusual.”
A stop sign controls the intersection for eastbound traffic where the Expedition proceeded through, he said, adding, “It’s unclear as of yet whether that vehicle stopped or not before entering the intersection.”
Special agents from the Department of Homeland Security have initiated a human smuggling investigation, an agency spokeswoman said on Wednesday.