Insurgents stormed the western Iraq city of Ramadi on Sunday and tried to blast their way into a police compound, setting off a fierce gun battle with local security forces. Eight police officers and seven insurgents were killed, according to government and security officials.

“It was a bold attack, surprising attack,” said Brig. Gen. Khamis Jasem, a commander at a provincial operations center. “They made the security forces busy with explosives here and there. Then they attacked.”

An additional six civilians were killed in the bombings and attacks, said Maj. Mahmoud Khaleel of the Anbar provincial police. Security officials have increased their readiness, particularly in the nearby city of Fallujah. “We are expecting similar attacks in the coming days,” Jasem added.

Sunday’s assault, in a predominantly Sunni area, followed a huge blast Saturday outside the southern city of Basra, which killed at least 53 Shiite pilgrims on a march to a religious shrine. The country is increasingly on edge after previous bombings in the wake of the U.S. troop withdrawal last month. Officials fear that insurgents are trying to provoke a sectarian war between Sunni and Shiite extremists, in part by taking advantage of a political crisis in Baghdad that has paralyzed the government.

The Ramadi assault began just before noon Iraqi time, Khaleel said. An explosive-laden car detonated outside an Investment Commission building. Another car bomb blew up outside Ramadi’s main water tank, Khaleel said. More charges erupted, including one outside a Sunni endowment building.

The final blast came from a suicide bomber wearing a vest with explosives. He detonated himself outside the main gate of the city’s police compound, which houses a jail, an investigation bureau and a counterterrorism operation, Khaleel said.

The insurgent was trying to clear the way for others. But police repelled the advance, Khaleel said, and chased the insurgents into a nearby empty building.

They killed seven of nine insurgents, said Hakmet Jassim, deputy governor of the province. But two remained at large Sunday evening, said Jasem, the brigadier general.

He said the slain insurgents were Iraqis. Forensic specialists and investigators were still trying identify them late Sunday, he said.

The terrorist group al-Qaeda in Iraq has operated in the area in the past. Jasem indicated they were behind Sunday’s killings. “No one does such attacks except al-Qaeda,” he said.

A leading sheik in the area, Hammed al-Hies, blamed the assault on larger issues facing Iraq.

“All these attacks happened because of the political problems in the country and the corruption that spread inside the body of the security agencies and the judicial systems,” said Hies, chairman of the Salvation Council of Anbar.