An apparently coordinated attack against two Shiite mosques in a town where Iraq's two main Muslim sects had lived peacefully has raised concerns about religious and ethnic strife as Shiites and Sunnis jockey for power in postwar Iraq.

Five people were killed and dozens wounded when an explosion ripped through worshippers streaming out of Sadiq Mohammed (search) mosque following prayers on Friday, Islam's holy day.

Ninety minutes earlier, police defused a car bomb outside another nearby mosque. The bomb was packed with 330 pounds of TNT and rigged with four artillery shells that would have doubtless caused many more fatalities.

"We've been living peacefully. There has never been a problem," said Hamid Jomoa, a 28-year-old Sunni preacher who rushed to the scene to help.

But with sectarian tensions mounting, the U.S.-led occupation force has been accused of stirring up trouble, with some at the scene of the bombing even suggesting U.S. forces had fired a rocket at the mosque.

Many Iraqis believe the United States and its allies are trying to foment disorder as a pretext for continued rule, despite American assurances to the contrary. Others believe some countries in the region could be financing attacks to keep Iraq, which has the world's second-largest oil reserves after Saudi Arabia (search), divided and weak.

"This attack aims at igniting sectarian disputes," said Salah Hassan. "This is a Jewish-American scheme."

Under Saddam's authoritarian rule, which gave the Sunnis dominance, ethnic and religious divisions were largely kept in check. Since Saddam's fall in April, religious leaders on both sides have tried to prevent an outbreak of tensions.

But Iraq's Shiites, a majority in the population of 25 million, also have an opportunity to end decades of subjugation.

Also raising tensions are increasingly strident demands by Kurds (search), who are ethnically different from Arabs and dominate in the north. The Kurds want to expand in territory and in power the Switzerland-sized area they have ruled autonomously under the protection of a U.S.-enforced no-fly zone since the first Gulf War ended in 1991.

Demands that the oil-rich city of Kirkuk join the Kurdish territory have roused Turkic and Arab residents to violent protests, and militants have turned to assassination.

A Kurdish man who was walking in an Arab neighborhood of Kirkuk was gunned down and killed on Friday, the city's Police Chief Torhan Youssef reported.

Earlier, Youssef said coalition soldiers mistakenly killed two Iraqi police officers who were walking around with their AK-47 assault rifles after dark but were not wearing identity badges.

U.S. spokeswoman Maj. Josslyn Aberle said they were killed by soldiers who saw two men firing at a house. Aberle said the two, later identified as police officers, were killed after they refused to put down their arms even after soldier fired warning shots.

Elsewhere in Iraq, U.S. soldiers kicked open doors and dragged men out of their beds before dawn Friday in a raid aimed at Saddam loyalists in his hometown of Tikrit. The military said they detained 30 men -- including 14 suspected of orchestrating, financing or carrying out attacks on American soldiers. Among them was a man believed to have detonated a bomb that killed a female soldier from Texas.

The raid came hours after a Black Hawk medevac helicopter was shot down Thursday near Fallujah, a town west of Baghdad that is a stronghold of resistance to the U.S. occupation. All nine U.S. soldiers on board were killed.

A military statement said Saturday that soldiers were continuing to recover parts of the helicopter and that "investigations continue to assess what brought the aircraft down."

A witness at the scene told the AP that he saw a rocket hit the tail of the helicopter.

It was the third U.S. helicopter forced down near Fallujah.

After the bombing in Bakubah (search), 35 miles northeast of Baghdad, wailing women tried to cover body parts as the wounded walked in a daze. A man screamed in anguish as he knelt before two bodies.

Two hours later, people were still picking up remains. Blood oozed down the street, where worshippers who couldn't fit into the small Sadiq Mohammed mosque had set up prayer mats.

The explosion was caused by a gas cylinder rigged with an explosive, U.S. officials said.

Suspicions had been raised because of the discovery 90 minutes earlier of the car bomb at the other Shiite mosque. Faulty wiring prevented it from going off and police defused it, according to a police investigator who spoke on condition of anonymity.