Baghdad ? Three Iraqi soldiers threw themselves on a suicide attacker wearing an explosives vest at an Army Day celebration Sunday – an act of heroism the U.S. said likely prevented many more deaths. Iraqi police said at least 11 people were killed in the blast, the deadliest in a series of bombings in Baghdad.

One of the attacks in the capital killed an American soldier – one of two U.S. deaths announced on Sunday.

Shortly before the bomber struck the Army Day festivities, about two dozen Iraqi soldiers were standing outside the offices of a local nongovernmental agency pushing for unity in Iraq. The troops, their AK-47 rifles raised in the air, chanted pro-army slogans and a common anti-insurgent taunt: “Where are the terrorists today?”

Associated Press photographer Hadi Mizban was about five yards away from the suicide attacker when he blew himself up on a narrow street in the central Karradah area.

“The blast happened as civilians were giving flowers to soldiers and sticking them in the muzzles of their guns,” recalled Mizban, an Iraqi national. “It was a jubilant scene.”

Afterward, he said, the street was littered with bodies, weapons and shoes. Dazed soldiers and policemen carried their bloodied colleagues to nearby pickup trucks that whisked them to a hospital.

“There was a severed head on the street and some of the soldiers that I was photographing earlier were dead. Those who survived panicked, pulling back from the scene and shooting in the air,” said the 40-year-old Mizban.

Among the dead were four police officers, three Iraqi soldiers and four civilians, a police officer said on condition of anonymity because he was not authorized to speak to reporters. At least 17 people were injured.

“These martyrs gave their lives so that others might live,” said Lt. Col. Steve Stover, a U.S. military spokesman.