From the Associated Press: The U.S. Border Patrol says that one of its agents has been killed in southern Arizona.

Border Patrol spokesman Eric Cantu confirmed the agent’s death but had very few details to release Wednesday morning.

KOLD-TV in Tucson reports that the incident occurred just after 11 p.m. Tuesday in the Peck Canyon area north of Nogales.

Cantu tells The Associated Press the FBI is investigating the agent’s death. CNN reports that four people are in custody in connection with the incident.