Iraqi authorities say militants have raided a government security compound in the western city of Ramadi, killing at least seven policemen and wounding about 15 other people.
Officials say the assault began Sunday morning when the insurgents set off several bombs around the capital of Iraq's Anbar province. They say one assailant later blew himself up at the entrance to Ramadi's security headquarters, allowing his comrades to shoot their way inside and reach the roof of a building.
Iraqi security forces exchanged fire with the gunmen, killing some of them and retaking control of the complex after several hours.
The compound raided by the militants houses an anti-terrorism police squad and detention center. Government buildings in Ramadi have been frequent targets of insurgents in recent years.
Ramadi was a stronghold of Sunni militants linked to al-Qaida in the years after the 2003 U.S.-led invasion of Iraq. But local Sunni militias eventually turned against al-Qaida and sided with U.S. forces, helping to reduce violence in Anbar significantly.
In earlier violence on Saturday, a suicide bomber attacked Shi'ite pilgrims in the southern city of Basra, killing at least 53 people and wounding more than 130. The pilgrims were taking part in the Shi'ite religious commemoration of Arbaeen. There has been no claim of responsibility.
The United Nations' top envoy in Iraq, Martin Kobler, condemned Saturday's attack. He urged all Iraqis to maintain their shared values and break what he called the "vicious" cycle of violence in the country.
Iraq's government, headed by Shi'ite Prime Minister Nouri al-Maliki, is dominated by Shi'ites, but includes Sunnis and Kurds in a power-sharing system riven with sectarian tensions.
A series of attacks on Iraqi Shi'ites has killed more than 100 people since Maliki issued an arrest warrant for Iraq's Sunni Vice President Tariq al-Hashemi last month. Hashemi fled to Iraq's autonomous Kurdish region to avoid detention on charges of running a death squad. He denies the charges.
Some information for this report was provided by AFP and Reuters.