BAGHDAD, Iraq (CNN) -- A U.S. soldier fired on his fellow troops at a counseling center at a base outside Baghdad, Iraq, on Monday, U.S. officials said, killing five people in the worst such attack of the six-year-old Iraq war. U.S. Army troops get a safety briefing before departing Camp Liberty, Iraq, in December 2008. The shooting occurred at 2 p.m. at a stress clinic at Camp Liberty, near Baghdad International Airport, two senior defense officials said. Though initial reports indicated the attacker was killed in the incident, the U.S. command in Baghdad said late Monday a suspect in the killings was in custody.
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Defense official: Suspect had been a patient at the treatment center
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President Obama to discuss incident with defense secretary
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Attack is the deadliest on soldiers by a fellow soldier during Operation Iraqi Freedom
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Five killed and three others wounded in incident
@placeholder is tightly guarded, and U.S. troops are required to clear their weapons of ammunition while on the base.