(CNN) -- A U.S. Army sergeant pleaded guilty Monday to gunning down five fellow service members at a combat stress clinic in Iraq after military prosecutors agreed not to seek the death penalty.
Sgt. John Russell admitted to the May 11, 2009, killings at Baghdad's Camp Liberty, telling a Joint Base Lewis-McChord court that he "did it out of rage," according to The News Tribune of Tacoma.
The court scheduled a May 6 hearing to determine whether Russell committed the slayings with premeditation, which the 48-year-old soldier has disputed. The outcome will determine whether Russell is sentenced to life without parole or given a lesser sentence.
As part of the plea agreement, Russell described to the court how he killed Navy Cmdr. Charles Springle, Army Maj. Matthew Houseal, Sgt. Christian Bueno-Galdos, Spec. Jacob Barton and Pfc. Michael Yates Jr.
It was the first time Russell has publicly detailed what happened at the combat stress clinic.
Russell, a communications specialist, was on his third deployment to Iraq.
His attorneys have argued Russell suffers from post-traumatic stress disorder, depression and a brain injury from previous combat, which make him not fully responsible for the killings.
CNN's Chelsea J. Carter contributed to this report.