A U.S. Border Patrol agent killed during a traffic stop near the Canadian border worked security duty at the Pentagon during the time of the Sept. 11 attacks.

Sources tell WCAX News that a third person may have been involved in the shootout that killed a Border Patrol agent during a traffic stop in Vermont.

David “Chris” Maland, the Border Patrol agent killed Monday, was shot while conducting a traffic stop in a Vermont town near the Canadian border, according to the FBI’s latest update on the case.