The 13 people killed in a crash between their SUV and a big rig in Southern California on Tuesday are suspected to have entered the U.S. illegally that morning, breaching a fence on the U.S.-Mexico border in a likely human smuggling attempt, according to Customs and Border Patrol.

“A 10-foot breach” in a fence between the two countries was reported Tuesday morning, and agents reviewed surveillance video which showed two “vehicles leaving the area in proximity of the fence breach,” border patrol said on Wednesday.

A Ford Expedition SUV carrying 25 people collided with the big rig, ejecting many of the SUV passengers onto the road, later on Tuesday, according to the California Highway Patrol.

Twelve people, including the SUV driver, died at the scene, and another person from the SUV died at a hospital, the highway patrol said.

“All are suspected to have entered the U.S. illegally,” border patrol said.

The accident was near Holtville in Imperial County, about 125 miles east of San Diego and about 10 miles from the U.S.-Mexico border.

Every survivor was injured to some extent, highway patrol said. Some suffered life-threatening head injuries, chest injuries and fractures, officials at El Centro Regional Medical Center said Tuesday.

Agents also found 19 people hiding in the brush by a red Suburban engulfed in flames and “determined they had entered the country illegally through the breach in the border fence,” border patrol said.

“We pray for the accident victims and their families during this difficult time,” El Centro Sector Chief Patrol Agent Gregory Bovino said in Wednesday’s statement released by border patrol.

“Human smugglers have proven time and again they have little regard for human life,” he added. “Those who may be contemplating crossing the border illegally should pause to think of the dangers that all too often end in tragedy.”

ABC News’ Alex Stone contributed to this report.