BAGHDAD, Iraq -- Suicide attackers detonated explosive-laden boats near oil facilities in the Persian Gulf on Saturday, killing two U.S. Navy sailors in a new tactic against Iraq's vital oil industry. Elsewhere, violence across Iraq killed at least 33 Iraqis and four American soldiers.
It was the first such maritime attack against oil facilities since U.S. troops invaded Iraqi more than a year ago.
In the attack, three dhows, or small boats, drew close to two major oil terminals in Gulf waters about 100 miles from Iraq's main port, Umm Qasr, and exploded when coalition craft tried to intercept them. A U.S. Navy craft was flipped by the blast, killing the American sailors and injuring five others, the U.S. military said.
Initial reports said there was no damage to the terminals, the military said.
The Gulf bombings came on a day of multiple attacks in Iraq: The deadliest was a roadside bomb that hit a bus south of Baghdad, killing at least 13 Iraqis. A mortar barrage struck a crowded market in the capital's biggest Shiite neighborhood, Sadr City, killing at least seven.
The U.S. soldiers were killed around dawn, when two rockets were fired from a truck and slammed into the base in Taji, 12 miles north of Baghdad, the military said. U.S. helicopter gunships then destroyed the truck. Seven soldiers were wounded, three of them critically, the military said.
Also, an Army reservist missing in Iraq since a convoy attack April 9 was confirmed dead. The remains of Sgt. Elmer Krause, 40, were found Friday, according to a statement Saturday from the Department of Defense. It gave no other details. Another soldier and a U.S. contract worker abducted in the same attack remain unaccounted for.
The latest deaths, along with the combat death of a Marine announced Saturday, brought to 108 the number of U.S. troops killed in Iraq since the beginning of April. The military announced the death of a soldier in a non-combat incident, bringing to 717 the number servicemembers who have died in the country.
Anywhere from 900 to 1,200 Iraqis have been killed in April -- depending on various reports of the death toll from Fallujah.
British military spokesman Hisham H. Halawi said the port at Umm Qasr, the chief southern outlet for Iraqi oil, remained open after the boat attacks.
The first blast came when a dhow was sighted near the Khawr al-Amaya oil terminal, the Bahrain-based U.S. 5th Fleet said. When an interception team tried to board, the dhow exploded, flipping the U.S. Navy craft.
About 20 minutes later, two more dhows were spotted near the al-Basra oil terminal. They, too, exploded when security teams approached, but there were no casualties among the security teams, the 5th Fleet said.
Halawi said the second dhows were trying to pull close to two tankers at the al-Basra terminal, also known as ABOT.
The oil attacks came three days after near simultaneous suicide car bombings in the southern Iraqi city of Basra -- 30 miles north of Umm Qasr -- that killed 74 people.
The violence came as U.S. commanders repeated warnings that they may soon launch a new assault on the besieged city of Fallujah, saying guerrillas had not abided by a call to surrender heavy weapons.
L. Paul Bremer, the top U.S. administrator in Iraq, traveled to the Marine base outside Fallujah for consultations Saturday, while Brig. Gen. Mark Kimmitt told reporters: "Should there not be a good faith effort demonstrated by the belligerents inside Fallujah, the coalition is prepared to act."
In Saturday's bloodiest incident, a bomb exploded on a main road as a bus passed near Haswa, 30 miles south of Baghdad. At least 13 people -- including a 4-year-old boy -- were killed and 17 wounded, said Wasan Nasser, a doctor at Iskan Hospital in neighboring Iskandariyah.
Civilians targetedIn Sadr City, the capital's sprawling Shiite slum, angry residents vented anger at Iraq's U.S. occupiers after the mortar attacks, which followed an early morning clash in the neighborhood between U.S. troops and militiamen loyal to a radical Shiite cleric, Muqtada al-Sadr.
Some of the mortar shells in Saturday's barrage against Sadr City, which killed at least seven people, hit two miles from any U.S. position -- suggesting they may have deliberately targeted civilians in the Shiite neighborhood.
Three shells pounded into the neighborhood's main souk, known as the Chicken Market, just as morning crowds were gathering to shop.
At least six Iraqis were killed and 38 wounded, said Yassin Abdel-Qader, a doctor in the area's Health Directorate. The Baghdad slum is home to more than 1 million people.
Hours later, a projectile struck a two-story house, killing a woman as she took an afternoon nap and wounding her daughter. At least two more landed later in the afternoon, hitting a main street on the edge of Sadr City, breaking windows but causing no casualties.
Before the mortar fire, U.S. troops launched a pre-dawn raid into Sadr City, pursuing al-Sadr militiamen. They were caught in a gunbattle in which two Iraqis were killed, according to U.S. Maj. Phil Smith.
"It was clearly an attack on civilians. There was no U.S. military at that spot," said Lt. Col. James Hutton of the Army's 1st Cavalry Division, which responded to the attack and helped treat the wounded.
Still, angry Shiites blamed the Americans for the assault. After one of the afternoon strikes, residents chanted, "Long live al-Sadr. America and the Governing Council are infidels."
In other violence Saturday:
An Iraqi woman working as a U.S. military translator was shot and killed with her husband as they drove to a U.S. base, a hospital official said.
A roadside bomb destroyed a car carrying Iraqis near a U.S. base in the northern city of Tikrit. Four Iraqis were killed and 16 wounded, the U.S. military said.
Polish troops clashed overnight with Shiite militiamen in the city of Karbala, killing five, a spokesman for the multinational peacekeeping force in south-central Iraq said Saturday.
AP correspondent Adnan Malik in Riyadh contributed to this report.