Little is known about Major Gen Nidal Malik Hasan, the gunman in the US army base shootout in Texas where 12 people have been killed and 31 others have been injured.

Hasan, 39-yr-old, is a US citizen of Jordanian descent.

He is a psychiatrist who previously worked at Walter Reed Army Medical Center but later he was practising at Darnall Army Medical Center at Fort Hood.

Officials are trying to determine if Hasan was his birth name, or if he converted to the Islamic faith at some point in his life.