Four people were killed in a shooting Wednesday at Fort Hood Army base in the US state of Texas, according to two US law enforcement officials.
The officials said the four dead include the shooter.
One of the officials, citing official internal Justice Department updates, said 14 others were hurt.
They spoke on condition of anonymity because they were not authorised to release information by name.
Fort Hood said in a statement posted online that its Directorate of Emergency Services had an initial report that the shooter was dead, but that the report was unconfirmed.
Reports circulating within the Justice Department indicated that the shooter died of what appears to be a self-inflicted wound, a US law enforcement official said.
The Army said on its official Twitter feed that the Texas Army post was still on lockdown.
Injured people were being treated at the post's Carl R. Darnall Medical Centre and other local hospitals.
US President Barack Obama vowed that investigators will get to the bottom of the shooting, seeking to reassure the nation whose sense of security once again has been shaken by mass violence.
In a hastily arranged statement, Obama said he and his team were following the situation closely.
He said the shooting brought back painful memories of the 2009, when 13 were killed at the same post in the deadliest attack on a domestic military installation in history.
Obama reflected on the sacrifices that troops stationed at Fort Hood have made - including during multiple tours to Iraq and Afghanistan.
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