Some Mosques Attacked, but Iraq Relatively Calm

Sunni insurgents were blamed for Wednesday's attack on the shrine, one of Iraq's most holy sites for Shiite Muslims. A bombing of the same mosque last year resulted in a bloody, sectarian confrontation between Shiites and Sunnis that left hundreds dead.

Immediately after the shrine was bombed, Iraqi Prime Minister Nouri al-Maliki put Baghdad and Samarra under an indefinite curfew in hopes of heading off a wave of violence. He also restricted vehicular traffic through Baghdad, a measure that is expected to remain in place until Saturday.

In addition, U.S. and Iraqi military patrols increased security on the streets of Baghdad and set up additional checkpoints on roads leading to the Sadr City neighborhood, a stronghold of Shiite cleric Muqtada al-Sadr's Mahdi Army militia.