Twelve people have been killed and 31 wounded in a shooting rampage at the Fort Hood US Army base in Texas.

The shooting began around 1:30 pm local time on Thursday. Lieutenant General Bob Cone said one shooter had been killed and two suspects had been arrested. All are US soldiers.

Officials identified the slain suspect as Major Malik Nadal Hasan. The Army said he was a mental health professional. The shootings were carried out at the base's Soldier Readiness Center, where soldiers undergo medical screening before and after deployment.

Fort Hood is the biggest US army base in the world. It is home to about 52-thousand soldiers. The base was locked down after the shootings.

US President Barack Obama has condemned the shootings, calling the incident an "horrific outburst of violence".