The federal officer killed while on duty near the Canadian border has been identified as a U.S. Air Force veteran who provided security at the Pentagon during the Sept. 11 attacks.

Federal agents are investigating after a US Border Patrol agent was shot and killed Monday afternoon on the highway in Vermont.

Agent David “Chris” Maland died in a shooting following a traffic stop, the FBI said. A second person killed in the incident was a German national in the country on a current visa, authorities said.