Marines battled Iraqi insurgents for hours in the volatile city of Fallujah (search), killing at least 13 Iraqis and wounding 14 others in a series of gunfights, mortar barrages and airstrikes, local officials said Friday.

The U.S. military said Saturday that 20 militants were killed. A military spokesman, speaking on condition of anonymity, said Saturday that the fighters were killed during clashes between 7:30 p.m. Thursday and 1 a.m. Friday.

Many of those wounded, including at least one child, appeared to be civilians injured by U.S. airstrikes, hospital officials said. The U.S. military said insurgents started the fighting Thursday night by ambushing a patrol and then fled into buildings to continue the battle. The Marines said they suffered no casualties.

In Baghdad (search) late Friday, a loud explosion shook buildings in a downtown area with many hotels housing foreigners. The source of the blast was not immediately clear, and the U.S. military said there was no word on casualties.

Iraq has been beset by surging violence in recent weeks, including a wave of kidnappings and a devastating car bombing in Baqouba on Wednesday that killed at least 70 people.

Interim President Ghazi al-Yawer (search) said the violence is a sign that militants are growing desperate.

"I think the bad guys, the enemy, the army of the darkness, is getting more helpless and hopeless. That is why they are stepping up these things. Time and the place is on our side," al-Yawer said after meeting Friday with Secretary of State Colin Powell, the highest-ranking U.S. official to visit since the return of sovereignty to an Iraqi administration last month.

Meanwhile, a deadline set by militants to save the life of a captive truck driver expired, but there was no word on whether they carried through with their threat to kill him. The militants, who were holding seven foreign hostages from India, Kenya and Egypt, had demanded that the hostages' Kuwait-based transportation company get out of Iraq.

In northern India, villagers demanding the hostages' release detained 37 foreign tourists, most of them from Britain, for 18 hours. The tourists were released Friday after police persuaded the angry villagers to let them pass.

In neighboring Jordan, the relatives of four Jordanian truck drivers held by a different militant group joined with fellow drivers in chanting "Death to America" during a protest march they said the kidnappers had demanded as a condition for the release of those hostages.

After the demonstration, the kidnappers called the relatives to say they were pleased with television reports of the protest and promised to free their captives Saturday, said Mohammed Abu Jaafar, whose brother Ahmad was one of the hostages.

In Fallujah, Marines and Iraqi troops engaged in an hours-long battle with insurgents that spilled into an industrial area of the city. Witnesses reported hearing aircraft on bombing runs and dozens of mortar rounds fired toward a nearby American base.

The military said the fighting began late Thursday when insurgents attacked a joint patrol of Marines and Iraqi soldiers with gunfire, mortars and rocket-propelled grenades.

The Marines responded with tank and artillery fire at the insurgents' mortar positions several hundred yards away, the military said. Insurgents fled into buildings, which the Marines targeted with airstrikes and artillery, the military said.

Twelve auto repair shops and two houses were reported destroyed.

An estimated 13 Iraqis were killed and 14 others were wounded during the fighting, said Dr. Salim Ibrahim at Fallujah General Hospital. He said he could not give an exact count of the dead because many bodies had been torn apart in the bombings.