BAGHDAD (Reuters) – A US soldier shot dead five fellow soldiers at a military clinic in Baghdad yesterday in an incident that the top US military officer suggested may have been triggered by stress.

US President Barack Obama said in a statement that he was shocked and deeply saddened by the “horrible tragedy.”

The soldier walked into a centre for soldiers who are experiencing stress and opened fire, killing the five, said a US military official who asked not to be named because the incident was still under investigation.

The shootings occurred at Camp Liberty, a sprawling military base northeast of Baghdad airport that houses thousands of US troops.

It was not immediately clear whether the victims were soldiers seeking treatment for stress or worked at the clinic, the official added.

“The shooter is a US soldier and he is in custody,” said Marine Corps Lieutenant Tom Garnett, a US military spokesman in Iraq. US officials said they would charge him later.

Admiral Mike Mullen, chairman of the US military’s Joint Chiefs of Staff, told a news conference at the Pentagon that the shootings had occurred in a place where “individuals were seeking help.”

“It does speak to me, though, about the need for us to redouble our efforts, the concern in terms of dealing with the stress. … It also speaks to the issue of multiple deployments,” Mullen said.

Obama said Defense Secretary Robert Gates briefed him on the incident, adding: “I will press to ensure that we fully understand what led to this tragedy, and that we are doing everything we can to ensure that our men and women in uniform are protected as they serve our country so capably and courageously in harm’s way.”