Thirty-two people were arrested Tuesday in the Shiite Muslim city of Karbala -- where an American lieutenant colonel was killed last week -- in a raid carried out by coalition troops and Iraqi police.
Authorities were searching for a group that seized an Iraqi official last week. Weapons and ammunition were also seized in the raid, officials said.
U.S. officials said only that the targets were "criminal elements" in the city. Polish authorities, who are in charge of security in that region, said more than 30 suspects in the killing of Lt. Col. Kim Orlando (search) have been detained.
U.S. troops also fired guns into the air to disperse a crowd at the Oil Ministry (search) in Baghdad after a woman objected to a search by a sniffer dog.
Meanwhile, in Fallujah -- where coalition troops have come under continuous attacks by insurgents and supposed Saddam Hussein loyalists -- troops of the 82nd Airborne Division (search) were back on the streets, one day after one paratrooper was killed and six wounded in an ambush. Two civilians, including a Syrian truck driver, were also killed.
Nine miles to the southwest of Fallujah, an American Humvee was ablaze after what local residents said was an attack by insurgents. U.S. troops were searching houses in the area.
Polish military spokesman Capt. Andrzej Wiatrowski said the raid in Karbala, 50 miles south of Baghdad, took place before dawn against a group that seized an Iraqi official last week in a dispute over a bus, triggering armed clashes between rival Shiite factions.
Troops and police later searched the home of a Shiite cleric, Khalid al-Kazemi. Three men and two women were detained for questioning, he said.
North of Baghdad, an explosion blamed on saboteurs damaged a petroleum pipeline carrying crude oil and natural gas to refineries in the capital, an Iraqi officer said Tuesday.
The blast occurred Monday evening near the town of Siniya, about 125 miles north of Baghdad, officials said.
Sabotage of pipelines and other infrastructure has become a major problem for the U.S.-run coalition and its Iraqi partners as they try to revive the country's giant petroleum industry -- the key to economic recovery.
A Polish military convoy traveling from Baghdad to Camp Babylon near Karbala was attacked with grenades but no one was injured, Polish officials said.
Tensions rose in Karbala last week after a transport official seized a bus owned by followers of radical cleric Muqtada al-Sadr and held him in the al-Mukayam mosque, where one of al-Sadr's offices are located.
That led to clashes between rival Shiite groups in which several people were killed or injured. The clash appeared to be part of a power struggle in the majority Shiite community between forces of al-Sadr, a strong opponent of the U.S. military occupation, and followers of religious leaders who have taken a more moderate stand toward the Americans.
Last week, al-Sadr called on U.S. forces to announce a timetable for their "imminent departure from Iraq" and said in the interim "they should not interfere at all with the Iraqi people."
The Oil Ministry incident, which produced no casualties, illustrated the cultural chasm that divides the U.S. occupation forces from ordinary Iraqis. At one point, fists and rifle butts flew between U.S. soldiers and ministry employees, but no serious injuries were immediately reported.
The confrontation began when 28-year-old Amal Karim showed up for work Tuesday and faced a routine search at the ministry entrance by U.S. soldiers.
When the Americans told her to submit her bag to a sniff-search by a dog, she refused, saying the bag held a copy of the Quran, Iraqi witnesses said.
Devout Iraqis often carry Islam's holy book with them, and Muslims consider dogs to be dirty, disease-spreading animals.
"When she refused, the American soldiers took the Quran out of her bag and threw it to the ground," said one woman, Zaineb Rahim. "Then the American soldiers handcuffed Amal."
Pushing and punching followed between soldiers and Iraqis, and soon about 100 Iraqis had gathered in angry protest outside the huge, modern building on Baghdad's northern edge, leading the Americans to fire shots in the air, the witnesses said.
As the protesters hoisted an Iraqi flag, officers of the tiny, newly formed Iraqi army appeared, trying to ease tensions.
"We don't want the Americans to search us," said employee Muhaid al-Hayani. "We want the Iraqi police to do the job. We don't want any Americans in the building of our ministry. We want them to leave."
Karim was eventually released and was summoned to the oil minister's office, colleagues reported.
The incident Monday in Fallujah began when insurgents attacked a dismounted patrol from the 82nd Airborne Division with a homemade bomb and small-arms fire.
Reporters and Iraqi witnesses said the paratroopers raked the area with return fire, then raided a mosque and houses looking for the attackers. They detained at least nine Iraqis, including a woman, residents said.
The bodies of the two civilians killed in the Monday attack -- an Iraqi and a Syrian truck driver -- were taken to Fallujah General Hospital. The Associated Press saw that one of them, Iraqi Nazem Baji, had a gunshot wound in the back of his head and his hands were tied in front of him with plastic bands similar.
"They (Americans) raided the house, shot him first in the leg, tied his hands and then shot him in the head," said the victim's brother, Dira'a Baji. Baji said his brother was the only male in the house when the Americans came.
The U.S. military press office in Baghdad said it had no information on the allegation and referred AP to the 82nd Airborne press office.
The Associated Press contributed to this report.