Updated

Two Border Patrol agents were rushing to help with a pursuit of some suspected illegal immigrants Thursday when they entered a marked railroad crossing and their SUV was struck by a freight train, killing both agents, authorities said.

The wreck happened in a rural, farming area near Interstate 8 and the town of Gila Bend, about 85 miles southwest of Phoenix.

Yuma Border Patrol sector spokesman Agent Kenneth Quillin said the two agents were trying to position themselves on a road north of some other agents who were chasing a group of suspected illegal immigrants.

The suspected illegal immigrants were on foot, and none of them have been arrested, he said.

"We do see groups on a regular basis traveling through this area," Quillin said. The Border Patrol would not say whether the suspects were smuggling drugs.

The crash happened at a railroad crossing that is marked but does not have railroad crossing arms, Quillin said.

The freight train pushed the SUV down the tracks before coming to a rest. Television video from the scene showed a mangled black SUV in front of the train's engine. Tarps were placed over some of the wreckage.

Maricopa County Sheriff's Lt. Aaron Douglas said sheriff's detectives and the FBI will be jointly investigating the crash.

The agents who died were assigned to the Yuma sector, Border Patrol Agent Michael Espinoza said. Their names were withheld pending notification of family.

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Associated Press writers Mark Carlson and Bob Christie in Phoenix contributed to this report.