Two U.S. soldiers and a Border Patrol agent were killed and a fourth person was injured when a helicopter went down near Rio Grande City, Texas, on Friday, officials said.

The UH-72 Lakota helicopter crashed around 2:50 p.m. local time while it was “conducting aviation operations” in the area, according to a statement from the Defense Department’s Joint Task Force North.

The helicopter had been assigned to a support mission at the Southwest border of the U.S., the statement said.

The Joint Task Force North said it will not release the names of those who were killed until next of kin is notified. The person who was injured is a soldier.

The cause of the crash is under investigation.

Sen. John Cornyn, R-Texas, said on X that he is sending his “deepest condolences to the families of the National Guard soldier & Border Patrol agent who passed away & those who were injured in a helicopter crash near La Grulla, TX.”

Rio Grande City is on the border of Texas and Mexico.