TUCSON, Ariz. (AP) — Border Patrol officials say an agent has fatally shot a man in a remote area of Arizona.

They say the agent was being assaulted Wednesday by a man in a group of people believed to be in the country illegally.

Further details on the assault weren't immediately available.

Border Patrol officials say the Tucson Sector agent shot the man in the Baboquivari Mountain Range and he later died of his wounds.

Three members of the group have been taken into custody and agents are searching the area for others.

The name of the agent and the man killed haven't been released.

Authorities say the shooting is being investigated by the FBI, Tohono O'odham Nation police and the U.S. Customs and Border Protection.