The US Army's Fort Hood has reported an active shooter to Texas authorities.
The base was the scene of a mass shooting in 2009, when 13 people were killed and more than 30 wounded in what was the deadliest assault on a domestic US military installation in history.
Bell County Sheriff's Office Lieutenant Donnie Adams says the sheriff's office dispatched deputies and troopers from the Texas Department of Public Safety to the nearby Texas Army base.
Fort Hood ordered everyone at the base to "shelter in place". The order was sent tonight on the base's Twitter feed and posted on its Facebook page.
The 1st Calvary Division, which is based at Fort Hood, sent a Twitter alert telling people on base to close doors and stay away from windows.
A spokeswoman for the base declined to comment.