At least 31 Iraqis were killed and 71 wounded in a double suicide bombing north of the capital Thursday, police and hospital officials said.
The U.S. military, meanwhile, announced the death of a U.S. soldier in a car bombing in Baghdad.
In the attack in Balad Ruz, a religiously mixed town in Diyala province, police said a woman with explosives hidden under her robes blew herself up in a market. As rescue workers arrived, a male suicide bomber struck, police said.
The U.S. military put the initial toll at 26 people killed and 52 injured; but hospital officials said the numbers were higher.
Sami Abdullah, who sells women's clothing and makeup, was inside his store when the first bomb went off.
"After the smoke and dust settled, I saw the torn-up bodies on the ground," he said. "I saw persons who had their arms or legs missing, people between life and death."
After the second bombing, Abdullah saw a driver dead behind the wheel of his ambulance and police officers lying wounded in the street, he said.
Coordinated attacks are a hallmark of Sunni Arab militants loyal to Al Qaeda in Iraq, a largely homegrown group that the U.S. says is foreign-led.
U.S. officers blamed Sunni insurgents for the bombing that killed the American soldier and injured two others Thursday in Baghdad. The blast also killed nine Iraqi civilians and injured 23, Iraq's Interior Ministry said. Residents chased down the man they said had parked the explosives- laden car and turned him over to police, military officials said. Two other suspects also were taken into custody.
At least 4,065 U.S. service members have died since the start of the war in March 2003, according to the independent website icasualties.org.
Meanwhile, clashes in Baghdad continued as U.S. and Iraqi troops enforced a crackdown against Shiite militiamen.
Hospital officials in Baghdad's Sadr City district said they had received 19 bodies and had treated 32 injured since late Wednesday. Police said at least five other people were killed and 17 injured in clashes elsewhere in the capital.
The U.S. said its forces killed at least five fighters in exchanges Thursday with suspected Shiite militiamen.
Special correspondents in Baghdad contributed to this report.