Clashes between Iraqi security forces and masked insurgents broke out in the northern city of Mosul on Wednesday, resulting in 22 people killed and dozens wounded.

Armed insurgents dodged and sprinted through the city's Yarmouk and New Mosul districts, according to al-Jazeera and al-Arabiya satellite television networks, attacking a police station and the home of Iraq's interim president, Ghazi Yawar, who was in Baghdad.

The U.S. military said eight insurgents and 14 civilians were killed in the fighting. The extent of casualties among Iraqi police officers and national guardsmen was unclear.

Also on Wednesday, four Jordanian hostages held for more than a week in Fallujah were freed after what was described as a raid at the hideout of their captors. In addition, two Turkish hostages were released after their employers agreed to stop trucking goods into Iraq.

Meanwhile, two Marines were killed and four wounded in attacks near Qaim, in western Iraq near the border with Syria. According to military officials, one was killed by a roadside bomb as he and other members of a patrol investigated reports of an explosion near an Iraqi police checkpoint. The Marine, a member of the 3rd Battalion, 7th Marine Regiment, was evacuated quickly by helicopter but died soon afterward.

During a search of the area after the blast, a second Marine in the battalion was shot and killed as he strung concertina wire across a road.

The injuries of the four wounded Marines were not life-threatening, according to a spokesman in Qaim. The names of the dead were being withheld until their families were notified.

Qaim has been the site of frequent attacks on U.S. forces, but Wednesday's incident was unusual in that gunfire was coordinated with a roadside bomb.

In the city of Tall Afar just west of Mosul, soldiers from the Army's 2nd Infantry Division killed one insurgent and captured three after finding them driving in a suspicious manner near a major intersection, the U.S. military said.

After the driver attempted to flee, the soldiers rammed the car with a military vehicle, killing one of the occupants. The soldiers found grenade launchers, a mortar tube, hand grenades, a machine gun and rifles in the vehicle, the military said.

Iraq's interim government is struggling to establish control in the face of a relentless insurgent campaign of car bombings, kidnappings and assassinations of government leaders.

Saudi Arabia has proposed a military force from Muslim countries to help Iraq quash the insurgency. Iraq's interim leaders have embraced the idea, but at a news conference in the capital on Wednesday, Yawar said the Muslim troops should supplement the U.S.-led security forces rather than replace them, as some senior Saudi officials suggested this week.

"Why should we bring forces as an alternative to other forces?" Yawar said. "It is not acceptable to replace a [soldier's] boot with another. Many of the effective Islamic countries are rejecting coming here. With my due respect to some countries, why should I replace someone whom I suffered to get him to learn here with another to start learning again? This is not acceptable."

Yawar also said countries sending troops to Iraq should contribute a sizable force. Such troops "should not be symbolic in number as if they are in a carnival, 40 or 50, and whenever they have any trouble they return home," Yawar said. He criticized the Philippines, which dispatched 51 troops to Iraq, then withdrew them early to secure the release of a kidnapped Filipino truck driver.

In Washington, the State Department said in a statement that the United States reaffirmed its "solidarity with the Iraqi people, who have been the main target of fanaticism and terrorist attacks. . . . We're united in our resolve to make no concessions to terrorists, nor to succumb to terrorist threats."

More than 70 foreigners have been taken hostage since this spring, including many truck drivers. Most have been released, but a Turkish truck driver was executed Monday by his captors, who call themselves the Monotheism and Jihad Group. The group has asserted responsibility for the beheadings of American businessman Nicholas Berg, South Korean translator Kim Sun Il and Bulgarian truck driver Georgi Lazov.

After the Turk's execution, the association representing the country's trucking industry announced it was halting deliveries to the U.S. military and other American clients in Iraq. Cahit Soysal, who heads the International Transportation Association, said the suspension would affect 200 to 300 trucks daily. The association did not say how long the stoppage would last.

The U.S. military's main supplier, KBR, a subsidiary of Halliburton Co., said its convoys were running as scheduled.

"While our ability to continue to receive goods from Turkey may be limited by the strike, we do not expect there will be significant interruptions to operations," said Stephanie Price, KBR's Middle East spokeswoman. "If the strike continues, KBR may have to assess alternate supply plans for the impacted locations. That is not the case today."

In one bright spot on Wednesday, the U.S. Army Corps of Engineers said it brought a new generator on line at the Baiji Power Plant, about 125 miles north of Baghdad, adding 20 megawatts of electricity to the Iraqi grid, enough to power 60,000 households.

Mitchell Frazier, a spokesman for the Corps of Engineers, said another 130 to 140 megawatts should be added within the next week. Each megawatt can supply about 3,000 households, according to Corps estimates, meaning the added capacity would serve nearly half a million homes.

Reconstruction of Iraq's power grid has been one of the most persistent challenges facing the U.S.-led effort here. Residents of Baghdad, used to nearly full-time power under the ousted government of Saddam Hussein, have been hit with rolling blackouts in recent weeks.

Frazier said he had lunch with a local tribal sheik at a downtown Baghdad hotel on Wednesday. Over a simple meal of chicken and rice, he asked the sheik what the Iraqi people needed most.

"Electricity," Frazier said the sheik told him. "He said when the AC goes off during the day, people go outside, and that's when there is trouble. When the power is off at night and people don't have lights to protect their homes, that's when there is trouble."

Correspondent Doug Struck in Qaim contributed to this report .

Two women and a man were killed when a car was caught in the crossfire between Iraqi security forces and insurgents in the northern city of Mosul.