A 27-year-old man was killed Monday after opening fire at a U.S. Border Patrol facility in McAllen, Texas, authorities said.

Federal agents returned fire at Ryan Louis Mosqueda, who had an assault rifle and was carrying a utility vest, McAllen Police Chief Victor Rodriguez told reporters Monday morning.

Law enforcement said they found another rifle and more ammunition. Rodriguez said the man’s motive is currently unknown.

One officer was injured in the shooting, but Rodriguez said it was unclear if the injury was from shrapnel or a bullet.