The Fort Hood US military base in Texas has ordered all staff to take shelter amid reports of an active shooting situation that had left several people wounded.
"All personnel on post are asked to shelter in place,” the US base, where an army officer killed 13 people in a 2009 shooting rampage, said on its Twitter feed.
One person is dead and 14 have been wounded, a senior defence official told Associated Press.
There one fatality is believed to be a gunman but there is speculation there was a second gunman.
Local news outlets are reporting that officials at Fort Hood, Texas, have confirmed an on-base shooting incident that has placed the military installation on lockdown.
Local station KCEN-TV is saying that it has reports that several people have been injured, with at least one patient being taken to a hospital.
Several local reports say one person is confirmed dead.
The shooter may also still be at large.
CNN reported that one shooter was dead, and that police were pursuing a second shooter.
NBC News is reporting that a shooter is in custody, but authorities are looking to into the possibility of more than one shooter.
There are a multiple conflicting reports on the number of injuries, but almost all local news outlets have reported that one person was killed.
The only statement given by Fort Hood is: "There has been a shooting at Fort Hood and injuries are reported. Emergency crews are on the scene. No further details are know at this time."
A witness described a suspected gunman as being a white male in a gray Toyota car, using a .45 pistol, KCEN TV said, adding that he was believed to have been in a medical building on the base.
On November 5, 2009, Major Nidal Hasan opened fire at a medical facility in the sprawling Fort Hood base that serves as a staging point for soldiers to deploy to combat zones.
Twelve of the dead and 30 of the wounded were soldiers. Hasan was captured after he was shot by a civilian police officer who responded to the attack.