A Southeast Missouri State University graduate died over the weekend in Iraq.

U.S. Army 1st Lt. Daniel P. Riordan, 24, of St. Louis was killed Saturday in Taji, Iraq, when an improvised explosive device exploded near his vehicle, according to information released by the Department of Defense. Riordan was stationed at Fort Hood, Texas.

Riordan is a December 2005 graduate of Southeast Missouri State University. He joined the military in November 2005 as an infantry officer and had been assigned to the 2nd Battalion, 8th Cavalry Regiment of the Army's First Cavalry Division since August. Riordan was deployed to Iraq in November.

Three other soldiers were killed in the incident, according to the DOD: Sgt. Joel A. House, 22, of Lee, Maine; Sgt. Jimy M. Malone, 23, of Willis Point, Texas; and Spc. Derek A. Calhoun, 23, of Oklahoma City, Okla.

Fort Hood spokeswoman Nancy Bourget said she didn't have information about the mission the four soldiers were performing when they were killed.

Riordan was the recipient of the Purple Heart, Bronze Star Medal, Global War on Terrorism Service Medal, National Defense Service Medal, Army Service Ribbon, Overseas Service Ribbon and Combat Infantry Badge.

Check back at semissourian.com or read Wednesday's newspaper for more details.