The Pentagon officials have revealed that two other have been injured in the incident and that the gunman is now in custody.
The US president who was shocked by the incident has called it a 'terrible tragedy' and is planning to discuss it with Defense Secretary Robert Gates.
This is the second case of 'fragging' with an US soldier open firing at the fellow comrades. A soldier had killed 2 and injured 14 others with grenades and a rifle at a camp in Kuwait, and was sentenced for life in 2005.
This incident has brought attention to combat stress and morale of the troops in Iraq.