A U.S. Army sergeant has pleaded guilty to fatally shooting five fellow servicemembers at a combat stress clinic at Camp Liberty in Baghdad. The 2009 shooting rampage was among the worst acts of violence by a U.S. servicemember against other soldiers in the Iraq War. During a military court hearing Monday, Sgt. John Russell said he was in a “rage” at the time of the shooting and “wanted the pain to stop.” Russell reportedly suffers from post-traumatic stress disorder, among other mental health problems. He faces up to life in prison.