A soldier was detained in Iraq after he allegedly opened fire on a superior and another unit member, killing them both, the Army said Wednesday.

The soldier was subdued by other troops, and medics tried unsuccessfully to save the wounded soldiers, said Maj. Gen. Anthony Cucolo, commanding general at Fort Stewart in southern Georgia, where the soldiers' unit is based.

An Army spokesman said the shooting happened Sunday in Tunnis, Iraq. The slain soldiers and the alleged shooter, whose name was not released, belong to the 4th Brigade Combat Team of the 3rd Infantry Division.

The Army identified the slain soldiers as Staff Sgt. Darris J. Dawson, 24, of Pensacola, Fla., and Sgt. Wesley R. Durbin, 26, of Hurst, Texas. Both were assigned to the brigade's 3rd Battalion, 7th Infantry Regiment.

"We also know the accused is in custody — in control of military authorities in theater for now — and the investigation is under way," Cucolo said in a release that gave few other details.

A defense official in Washington, D.C., said the alleged shooter is a sergeant who was in a meeting to discuss his leadership performance with Dawson, who was his squad leader, and Durbin, who was a fellow team leader in the squad. The official spoke on condition of anonymity because details of the incident have not been released.

Fort Stewart spokesman Kevin Larson said he did not know if the soldier in custody had been charged by military authorities.

Dawson's stepmother, Maxine Mathis, said the Army had told the soldier's family few details other than that he was killed by a fellow U.S. soldier.

"I can't say he died for his country, dying like that," a weeping Mathis said from her home in Pensacola.

Cucolo called the deaths "a tragic and senseless loss of two professional soldiers ... who were also husbands and fathers."

Mathis, whose husband is Dawson's biological father, said her stepson joined the Army immediately after graduating from high school six years ago. He was serving his third combat tour in Iraq, and had re-enlisted not long before he was killed.

Mathis said he told her, "Momma, I'm not so afraid of the enemy. I'm afraid of our young guys over there, because they're so jumpy and so quick to shoot."