Authorities at the U.S. Army base at Fort Hood, Texas say gunfire has erupted at the facility and that several people have been wounded.
Officials at the huge base, the scene of a mass shooting in 2009, confirmed Wednesday's shooting after it was first reported on social media. The military statement offered no other details. Area news outlets are reporting multiple injuries.
The White House said President Barack Obama has been informed of the shootings and will receive updates through the evening.
Television footage showed helicopters overhead as military police searched the area. Nearby civilian police agencies were reported searching vehicles and sealing the perimeter of the base, located south of the city of Waco.
Fort Hood was the scene of a mass shooting spree in 2009. Thirteen people were killed and more than 30 others wounded when an Army psychiatrist opened fire on personnel.
After that shooting, the Pentagon ordered tightened security at all U.S. bases.