Fort Hood is the Army's largest U.S. post, with about 40,000 troops. It is home to the Army's 1st Cavalry Division and elements of the 4th Infantry Division, as well as the 3rd Armored Cavalry Regiment and the 13th Corps Support Command. It is located near Killeen, Texas.

At least seven people are dead and between 12 and 15 wounded in shootings at Fort Hood in Texas on Thursday. The incident took place at the sports dome, now known as the soldier readiness area, the station reported.

One person has been arrested and at least one more is on the run, reports say. The base has been locked down.

NBC News network said the two suspects were in military uniform and that the shooter-at-large was believed to have a high-powered sniper rifle.

White House spokesman Robert Gibbs said President Barack Obama had been briefed on the incident.

On the Fort Hood Web site, the word "closed" is posted with the statement, "Effective immediately, Fort Hood is closed. Organizations/units are instructed to execute a 100 percent accountability of all personnel."

In June, Fort Hood's commander, Lt. Gen. Rick Lynch, told that he was trying to ease the kind of stresses soldiers face. He has pushed for soldiers working a day schedule to return home for dinner by 6 p.m., and required his personal authorization for anyone working weekends. At the time, two soldiers stationed there had committed suicide in 2009 -- a rate well below those of other posts.