BAGHDAD &

U.S. troops have questioned hundreds of people and detained 11 in the search for three American soldiers feared captured by al-Qaida during a weekend ambush south of Baghdad, the military said today.




For a fourth day, jets, helicopters and unmanned surveillance aircraft crisscrossed the skies over the sparsely populated farm area near Mahmoudiya, 20 miles south of Baghdad to search for the missing soldiers. U.S. and Iraqi troops &

backed by dog teams &

searched vehicles and pedestrians. Other teams peered into crawl spaces and probed for possible secret chambers in homes.




"We have conducted more than 450 tactical interviews and detained 11 individuals" as of Monday night, U.S. military spokesman Lt. Col. Christopher Garver said.




Garver said the Americans were also turning to the local population, which he said "continues to be helpful in providing tips."




Elsewhere, two bombs hidden in plastic bags exploded in shops in central Baghdad, killing at least seven people and wounding 17, and dozens of suspected insurgents attacked a village north of the capital, killing five civilians and wounding 14, Iraqi authorities said.




On Monday, the Islamic State of Iraq &

an al-Qaida front group that claims it has the soldiers &

warned the U.S. to halt its search by about 4,000 troops, and the Pentagon acknowledged for the first time that it believes the soldiers are in terrorist hands.




Last June, al-Qaida claimed responsibility for the deaths of two U.S. soldiers whose mutilated bodies were later found in the same area.




If all three soldiers now missing are taken hostage alive, it would be the biggest single abduction of U.S. soldiers in Iraq since March 23, 2003, when Pvt. Jessica Lynch and six others were captured in an ambush near Nasiriyah in which 11 Americans were killed.




The three were last seen before a pre-dawn ambush Saturday that destroyed several Humvees in a U.S. convoy and killed four Americans and an Iraqi soldier traveling with them.




At 9:15 a.m. this morning a bomb hidden in a minibus leaving a bus stop on a main road in Mahmoudiya exploded, wounding three Iraqi passengers, police said.




Al-Qaida has been active for years in the string of towns and villages south of the capital, a mostly Sunni region known as the "triangle of death" because of frequent attacks on U.S. and Iraqi forces as well as Shiite civilians traveling to shrine cities in the south.




During the search Monday, U.S. and Iraqi forces exchanged fire with gunmen near the town of Youssifiyah, killing two and injuring four, an Iraqi army officer said.