PHOENIX (AP) - The Border Patrol says one of its agents was killed and another wounded in a shooting early Tuesday in Arizona near the U.S.-Mexico line.

The Border Patrol said in a statement the agents were shot while patrolling on horseback in Naco at about 1:50 a.m. MST Tuesday.

George McCubbin, president of the National Border Patrol Council, said a third agent was not harmed.

Cochise County Sheriff's spokeswoman Carol Capas said an alarm was triggered on one of the many sensors along the border and the three agents went to investigate. She said no suspects have been identified, and it is not known whether the agents returned fire.

The last U.S. Border Patrol agent fatally shot on duty was when Brian Terry was in a shootout with Mexican bandits near the border in December 2010. The shooting was later linked to the Fast and Furious gun smuggling oper ation.

The border patrol station in Naco was recently named after Terry.

Copyright 2012 The Associated Press.