Army officials said the base was on lockdown and personnel were told to enact active shooter protocols.
The four-story building involved is the headquarters for the Army's Combined Arms Support Command.
No other details were immediately available. The Department of Homeland Security uses the term "active shooter" to describe someone actively trying to kill people, usually in populated areas, with no pattern of choosing victims.
Fort Lee is about 200 kilometres from Washington and 40 kilometres south of the Virginia state capital, Richmond.