There are reports of an active shooter situation on the Fort Hood Army post in Killeen, Texas, KCEN-TV is reporting.
At least one person was killed, and an unknown number were injured, an Army spokesman told KWTX.
"There has been a shooting at Fort Hood and injuries are reported," said a statement from base public affairs. "Emergency crews are on the scene."
The shooter is still at large, and the post is currently under lockdown. People on post are being advised to stay away from windows and doors.
"All personnel on post are asked to shelter in place," wrote the official Twitter account of Fort Hood.
Fort Hood said police were responding to the shooting, which began around 4:25 p.m. local time, according to Ryan Wood, a producer at WFAA Channel 8.
KCEN reports the shooter is said to be in the Medical Brigade building.
Fort Hood was the same base attacked in 2009 by then-Maj. Nidal Hasan, who opened fire in a predeployment facility, ultimately killing 13 people and wounding 32 others.
At 340 square miles, Fort Hood is the largest U.S. military installation, according to NBC News.
This story is developing and will be updated as we learn more.