Suspected Mexican cartel members were caught on video opening fire on US Border Patrol agents near the southern border Monday – as a group of migrants reportedly tried to enter the US illegally, authorities said.

The ordeal unfolded at about 1:30 p.m. near Fronton, Texas, Customs and Border Protection said in a statement without revealing more details.

The apparent cartel members had started firing as the group of migrants were trying to cross the Rio Grande, Fox News reported, citing law enforcement sources.

Border patrol agents quickly returned fire, according to the Texas Department of Public Safety.