Baghdad, Iraq ? At least four American soldiers were wounded in guerrilla attacks Saturday, and the U.S.-led coalition said it thwarted a diesel-fuel smuggling operation, boarding a ship off the port of Umm Qasr and forcing it to return to shore.

A 173rd Airborne Brigade on patrol in Kirkuk came under rocket-propelled grenade and small arms fire, said Lt. Col. Bill McDonald, spokesman for 4th Infantry Division.

Two soldiers wounded in the explosion were in stable condition, McDonald said. The troops returned fire, he said.

In south-central Baghdad, two soldiers were wounded in a roadside-bomb attack on their armored Humvee, said Maj. Todd Mercer of the 82nd Airborne Division. The military provided no details on the soldiers’ condition.

And in the southern city of Basra, about 1,000 angry residents protested in the streets over cuts in electricity and water service and lines at gasoline stations. Three British soldiers were injured by stones.