The acting commissioner of the U.S. Customs and Border Protection said an agent died while out patrolling in Arizona.

Acting CBP chief Mark Morgan said Agent Robert Hotten was found unresponsive Sunday night.

"Last night, we lost one of our own, U.S. Border Patrol Agent Robert Hotten," Morgan tweeted. "Agent Hotten was found unresponsive while on patrol in AZ."

In a press conference CBP said it appears he had fallen and may have hit his head on some rocks, but the exact cause of death is unknown at this time.

According to Morgan, Hotten served for 10 years with  the U.S. Customs and Border Protection.

"My thoughts and prayers are with his wife, son, loved ones, and colleague," Morgan said.

Details surrounding Hotten's death were not immediately released.