A bomb attack that heavily damaged one of Iraq's most revered Shiite mosques has prompted a series of revenge attacks against Sunni mosques elsewhere.
Iraq's Interior Ministry says four men set off two bombs inside the Shiite shrine in Sammara, one of which dropped the famed golden dome.
It's not clear if anybody was hurt.
Authorities say three of the attackers wore black.
The other was wearing a military uniform.
Shiite leaders have called for calm, but at least five Sunni mosques have been hit in Baghdad and two more in the southern city of Basra.
The Samarra mosque houses the tombs of two Shiite Imams descended from the Prophet Muhammad.
There's been no claim of responsibility, but the government is blaming religious zealots bent on blocking formation of a new government.
U.S. and Iraqi forces have sealed off streets leading to the main Sunni mosque in Baghdad.