The victims of Tuesday’s deadly crash in rural California were probably undocumented immigrants who had crossed the border illegally during a smuggling attempt minutes before the collision, according to U.S. Customs and Border Protection officials.

Before California Highway Patrol troopers responded to the grisly crash, which killed at least 13 people, El Centro Sector Border Patrol agents reported that two vehicles had driven from Mexico through a 10-foot breach in the border fence 30 miles away, off Interstate 8 in Imperial County.

CBP spokesman Carlos Pitones said it appears smugglers cut into the fence, built in 2007, as part of a coordinated trafficking operation. That portion was built under the Secure Fence Act, which passed under George W. Bush.

The first to breach the fence was a large Chevrolet SUV that was later found engulfed in flames about 6 a.m., according to a CBP statement. Agents found 19 migrants hiding in the nearby brush, and they were taken into custody.

The second was a maroon Ford Expedition carrying 25 passengers that drove into the path of a large truck on State Road 115 on Tuesday. Surveillance footage confirms that the same Expedition seen driving through the hole in the fence is the same one that collided with the truck about 6:15 a.m., killing at least half of the occupants, including the 28-year-old driver.

The Border Patrol’s special trauma and rescue team responded to the crash to help the victims.

“Human smugglers have proven time and again they have little regard for human life,” El Centro Sector Chief Gregory Bovino said in a statement. “Those who may be contemplating crossing the border illegally should pause to think of the dangers that all too often end in tragedy.”

The Border Patrol is investigating the smuggling attempt.