The apparently coordinated attacks struck days after the last American forces left the country and in the midst of a major government crisis between Shiite and Sunni politicians that has sent sectarian tensions soaring.

The developments heighten fears of a new round of sectarian bloodshed like the one a few years back that pushed Iraq to the brink of civil war. The bombings bore all the hallmarks of Al-Qaeda insurgents. Most appeared to hit Shiite neighborhoods, although some Sunni areas were also targeted. In all, 11 neighborhoods were hit by either car bombs, roadside blasts or bombs attached to cars. There was at least one suicide bombing and the blasts went off over several hours.

The deadliest attack was in the Karrada neighborhood, where a suicide bomber driving an explosives-laden vehicle blew himself up outside the office of a government agency fighting corruption. Two police officers at the scene said the bomber was driving an ambulance and told guards that he needed to get to a nearby hospital. After the guards let him through, he drove to the building where he blew himself up, the officers said.

Figures gathered from Iraqi health and police officers across the city put the death toll at 67, and 160 injured.

For many Iraqis and the Americans who fought a nearly nine-year war in hopes of leaving behind a free and democratic country, the events of the past few days are the country's nightmare scenario. The fragile alliance of Sunnis and Shiites in the government is completely collapsing, large-scale violence with a high casualty toll has returned to the capital, and Prime Minister Nuri Al-Maliki is displaying an authoritarian streak and may be moving to grab the already limited power of the Sunnis.