Arrests in Shiite Shrine Bombing

The Iraqi national police have arrested 13 police officers who were guarding the al-Askariya mosque when it was attacked Wednesday, the U.S. military said today.

Among those arrested was the commander of the emergency service unit at the mosque. The military statement did not specify the charges, but U.S. military officials have told ABC News the bombs that destroyed the minarets at the revered Shiite shrine appear to have been planted inside the building, even as it was supposed to be under guard by the police commandos.

It remains unclear whether they were suspected of actually playing a role in the attack, were derelict of duty or were arrested for some other purpose.

Iraqi Prime Minister Nouri Kamel al-Maliki appealed for peace and rushed to Samarra Wednesday to search the rubble for answers. The No. 2 American commander, Lt. Gen. Ray Odierno, also came. Both wanted to know how the attack could have occurred under the watch of commandos who've guarded the mosque since it was first attacked last year.

From the mosque, Salahuddin Gov. Hamed Hamoud Shekti joined Maliki in an appeal for peace between Iraq's battling Sunni and Shiite Muslims.

"You are sons and grandsons of the two greatest imams who ever lived," said Shekti. "Please stop the sabotage and destruction, and work on the aims and goals of the city."

Despite the 6 p.m. curfew, sporadic gunfights have broken out in Baghdad and there were reports that four Sunni mosques had been attacked in Baghdad and farther south. In the capital's heavily fortified Green Zone, home to Iraqi and international agencies, a series of mortar strikes left brief plumes of smoke scattered along its skyline.

Thousands of Shiites ignored a curfew in Baghdad's Sadr City neighborhood today and lined the streets to protest the bombing of the Shiite shrine in Samarra. The protesters — many wearing the trademark black of the Mahdi Army — pledged their support of radical anti-American Shiite cleric Moqtada al-Sadr, chanting "Yes, yes, Moqtada."

In Samarra, Basra and in the Shiite holy city of Najaf, they also took to the streets.

Outside of Sadr City, where Sadr's organization makes its own rules, Baghdad was in lockdown after bombers attacked the al-Askariya mosque for the second time, toppling its 100-year-old minarets. The first attack on the mosque, the burial place of two of the 12 revered Shiite imams, crumbled the mosque's famed golden dome in February 2006 and launched sectarian bloodshed between Sunnis and Shiites that led Iraq toward civil war.

The top U.S. commander in Iraq, Gen. David Petraeus, told ABC's Charles Gibson that the U.S. military was scrambling to avert a recurrence.

"What we need to do is focus on the measures to be taken to make sure the emotions and the passion of the moment do not result in a cycle of violence that goes upward, as it did in 2006," Petraeus said.