Five U.S. service members were killed yesterday by a fellow soldier on an American military base in Baghdad yesterday. The soldier was later taken into custody. The center where the shooting occurred offered counseling services to soldiers seeking assistance and was considered a safe place for most servicemen. The killings appear to be the single deadliest episode of soldier-on-soldier violence among U.S. troops since the invasion six years ago.

Approximately one in six soldiers returns home with signs of post-traumatic stress. At least 140 soldiers committed suicide in 2008, according to the Army, a considerable increase compared with the 115 cases reported the previous year and the 102 documented in 2006. The number is the highest since the military started tracking suicide data in 1980. The Marine Corps, Navy and Air Force also reported an uptick in suicides last year.

For more on this tragedy and the military's reaction, we turn to Ernesto Londono, The Washington Post's Baghdad correspondent.

For more information on the shooting, watch the video below.