BAGHDAD, Iraq -- Suicide car bombers struck in Baghdad for the third time in a week Tuesday, this time outside the Turkish Embassy in yet another blow against those who would help the U.S. occupation. Witnesses said the driver and a bystander were killed, and hospitals said at least 13 were wounded.
In the southern city of Karbala, meanwhile, gunmen of rival Shiite Muslim factions clashed and witnesses said several people were killed or injured. It appeared to be part of a power struggle between forces of the firebrand cleric Muqtada al-Sadr and followers of religious leaders who take a more moderate stand toward the U.S. occupation.
Just who is behind the car bombings in the capital -- including two killing 18 other people in Baghdad in recent days -- remained a mystery, although Iraqis converging on the scene Tuesday began chanting pro-Saddam Hussein slogans.
"This is the act of those who want to turn Iraq into a terror paradise," said Turkish ambassador Osman Paksut, whose government has offered peacekeeping troops to reinforce the U.S. military presence here, a move strongly opposed by Iraqis.
Much of the blast was absorbed by concrete barriers outside the embassy, U.S. officials said. The bomber might have caught U.S. troops if he had struck last weekend, when they were deployed outside the mission in northwest Baghdad, apparently because of a threat.
"About three days ago, we received indications that there might be increased danger on the Turkish Embassy," said Col. Peter Mansoor of the U.S. 1st Armored Division. "We revved up security measures based on those indications."
He said the FBI and Iraqi police were investigating. Similar investigations of seven other vehicle bombings, killing more than 140 people across Iraq beginning in August, have made no known breakthroughs.
Following Tuesday's clash in Karbala, Pentagon officials said the U.S. military is concerned about al-Sadr but is uncertain whether he poses a significant threat. The officials, speaking on condition of anonymity, said they remain committed to disarming militias -- including al-Sadr's -- but declined to say whether they planned to confront his followers.
At his headquarters in Najaf, south of Karbala, al-Sadr demanded the Americans set a timetable for withdrawal. "Whoever cooperates with the occupation forces is not a Shiite. Indeed, they are not Muslims," he said.
In other developments Tuesday:
--A spokeswoman for the U.S. 4th Infantry Division, Maj. Josslyn Aberle, said the military did not have any reports that Saddam was hiding in his hometown of Tikrit. This countered a statement Monday by a 4th ID officer that the deposed president was recently in the area.
--Insurgents launched attacks on Iraqi police in the northern city of Mosul, killing one policeman and wounding two others in a drive-by shooting, the U.S. military said.
--In central Iraq's Sunni Muslim heartland, 100 people gathered at the main mosque in Fallujah to demand release of a cleric arrested Monday by U.S. troops. Sheik Jamal Shaker Nazzal is an outspoken opponent of the American occupation.
--The U.S. commerce secretary, Don Evans, delivered an upbeat message at a Baghdad news conference, saying, "We need to continue to focus on moving the entire country and region toward a more secure, hopeful and prosperous country and region." He said he had seen "endless successes" in Iraq, citing restoration of electrical power and reopening of schools and hospitals.
Tuesday's attack was the third car bombing since Thursday, when a driver detonated his vehicle in a police station courtyard in Baghdad, killing himself and nine others. On Sunday, a suicide bombing killed eight near the Baghdad Hotel, home to U.S. and Iraqi officials.
The string of attacks began in August with bombings at the Jordanian Embassy and the U.N. headquarters. All the targets have been institutions perceived as cooperating with the U.S. occupation.
The Turkish Embassy blast happened at about 2:45 p.m. as traffic streamed by the compound in the quiet, middle-class Waziriyah district.
"I was in a building across the street. I rushed over and saw that a car had exploded in front of the embassy," said Ahmed Hashim, 30, a graduate student at Mustansiryah University. He said the suicide driver's dismembered body was blown down the avenue, and a second person was also dead at the scene.
"I know that because I helped carry him into the ambulance," Hashim said. This was not immediately confirmed by U.S. or Iraqi authorities, but a painting contractor at the scene, Salah Khadhim, also said he saw a passer-by killed.
Mansoor, the American colonel, reported only the driver killed and two embassy workers injured. But officials at two hospitals said they received at least 13 wounded from the blast, including three seriously injured.
After the explosion, about 50 Iraqis gathered and chanted a pro-Saddam slogan -- "We sacrifice our blood and soul for you!" -- and waving Iraqi banknotes with the ousted dictator's portrait. Police fired in the air to disperse them, and detained several.
Popular suspicions in the bombings have focused on Saddam upporters, also blamed for repeated attacks on American troops, or on al-Qaida adherents or other Muslim extremists.
Asked whether the bombing was related to the issue of Turkish peacekeepers in Iraq, Mansoor said: "I think it has everything to do with that."
The Turkish parliament last week approved sending in peacekeeping troops in the coming months. Iraq's Governing Council has opposed the idea, because of the bitter legacy of centuries of Turkish colonial domination of the region.
The Turkish Foreign Ministry indicated the attack would not affect an eventual troop deployment. "Turkey will persevere with its efforts with determination," it said.
In Washington, State Department spokesman Richard Boucher said such attacks would not deter the U.S.-led coalition and the Iraqi people.
"The United States, our close ally Turkey, and the international community stand with the majority of the Iraqi people as they seek to peacefully build a free and stable country," he said.