Updated

Two SUVs involved in separate crashes in California on Tuesday entered the U.S. from Mexico through a 10-foot gap in a border barrier, federal investigators confirmed Wednesday.

One of the SUVs, said to have 25 illegal immigrants crammed inside, soon became involved in a deadly crash at State Highway 115 and Norrish Road in Holtville that killed 12 of the vehicle’s occupants at the scene and a 13th a short time later, officials said. Ten of the dead were Mexican citizens, according to the Mexican government, while the nationalities of the three others were not immediately clear.

The other SUV was found in flames about 10 minutes after entering the U.S., with 19 people spotted hiding nearby in the brush, the Los Angeles Times reported. It was unclear how the fire started.

Customs and Border Protection sources previously told Fox News a hole was cut in the border fence near Calexico, Calif. Both vehicles that drove through the hole somehow evaded a mobile camera system set up nearby, the sources added.

The hole in the fence appeared near Calexico, Calif. (Customs and Border Protection sources)

Gregory Bovino, the Border Patrol’s El Centro sector chief, said the incidents exemplified the disregard with which human smugglers treat their victims.

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"Human smugglers have proven time and again they have little regard for human life," Bovino told The Associated Press. "Those who may be contemplating crossing the border illegally should pause to think of the dangers that all too often end in tragedy -- tragedies our Border Patrol agents and first responders are unfortunately very familiar with."

"Human smugglers have proven time and again they have little regard for human life."

— Gregory Bovino, Border Patrol’s El Centro sector chief

At left is an opening in a metal fence along the U.S.-Mexico border in California. At right is a Ford Expedition SUV that crashed with a big rig, resulting in 13 deaths. (Border Patrol/Associated Press)

Border Patrol agents discovered the opening in the barrier at 6:05 a.m. Tuesday, then learned that the SUVs had entered the U.S. after reviewing surveillance video from the area, the Times reported. Just over an hour later, at 7:11 a.m., Border Patrol agents arrived at the scene in Holtsville where the vehicle carrying 25 people – a Ford Expedition – had collided with a big rig.

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Everyone riding in both SUVs was suspected to have entered the U.S. illegally, the Border Patrol said in a news release. Neither SUV was being pursued by Border Patrol personnel at the time of the accidents, investigators added.

The gap in the metal border fence appeared near the Gordon’s Well exit near Interstate 8, a Customs and Border Protection spokesman told the Times.

How long the opening existed – and whether more vehicles or pedestrians had entered the U.S. through that point – was not immediately clear. Nor was it clear if the damage to the barrier was repaired after Tuesday’s discovery.

Immigration and Customs Enforcement has launched a "human smuggling investigation" in connection with the fatal crash, the Times reported.

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The incidents unfolded during the height of the harvest season in California’s Imperial Valley agricultural area, the AP reported. The region supplies lettuce, onions, broccoli and more to supermarkets around the U.S.

The area where the crashes occurred started becoming known for illegal crossings in the 1990s, when heightened U.S. enforcement in San Diego pushed migrants to more remote areas, the AP added.

Fox News' William La Jeunesse and The Associated Press contributed to this report.