Backed by a barrage from warplanes and artillery, American troops fought their way into the western outskirts of Fallujah on Monday, seizing a hospital and two bridges over the Euphrates River in the first stage of a major assault on the insurgent stronghold.
The U.S. military reported its first casualties of the offensive — two Marines killed when their bulldozer flipped over into the Euphrates. A military spokesman estimated that 42 insurgents were killed across Fallujah in the opening round of attacks.
Four foreigners, including two Moroccans and two unidentified people, were captured when U.S. and Iraqi forces swept into the first objective: Fallujah's main hospital, which the military and Iraqi Prime Minister Ayad Allawi said was under insurgent control.
Iraqi soldiers stormed through the facility, blasting open doors and pulling handcuffed patients into the halls in search of gunmen.
After securing the hospital, U.S. and Iraqi forces started to take sporadic incoming fire, CBS News reporter Kirk Spitzer, embedded with U.S. troops, said.
Allawi said he had given the green light for international and Iraqi forces to launch the long-awaited offensive against Fallujah, considered the strongest bastion of Iraq's Sunni insurgents. "We are determined to clean Fallujah of terrorists," he said.
Allawi initially said 38 people were killed in the hospital seizure, but the U.S. military said no one was killed in the hospital operation. A military spokesman later gave a figure of 42 dead across the city since the Fallujah assault began.
Doctors in Fallujah reported 10 people killed and 11 wounded during the bombardment overnight.
In other recent developments:
Throughout the morning, artillery and mortars pounded targets in Fallujah and on its outskirts, and a U.S. jet swooped low to fire rockets at insurgent positions. An AC-130 gunship raked the city all night long with cannon fire, and before dawn, four 500-pound bombs were dropped, raising orange fireballs over the city's rooftops.
Outside the city, U.S. troops set up mortar positions and filled sandbags in preparation for an anticipated assault. U.S. troops clashed with insurgents in several locations along the outskirts of the city, firing rifle shots as they took cover around corners and behind the doors of their Humvees.
Commanders said the toughest fight was yet to come: when American forces cross to the east bank of the Euphrates and enter the main part of Fallujah — including the Jolan neighborhood where insurgent defenses are believed the strongest.
U.S. commanders have avoided any public estimate on how long it may take to capture Fallujah, where insurgents fought the Marines to a standstill last April in a three-week siege.
Marine commanders have warned the new offensive could bring the heaviest urban fighting since the Vietnam War. Some 10,000 U.S. Marines, Army soldiers and Iraqi forces are around Fallujah, where commanders estimate around 3,000 insurgents are dug in. More than half the civilian population of some 300,000 people is believed to have fled already.
Much depends on whether the bulk of the defenders, believed to be Iraqis from the Fallujah area, decide to risk the destruction of the city or try to slip away in the face of overwhelming force.
Another issue is the role of Iraqi forces fighting alongside the Americans. A National Public Radio correspondent embedded with the Marines outside Fallujah reported desertions among the Iraqis. One Iraqi battalion shrunk from over 500 men down to 170 over the past two weeks — with 255 members quitting over the weekend, the correspondent said.
Clerics in Fallujah denounced Iraqi troops participating in the assault, calling them the "occupiers' lash on their fellow countrymen."
"We swear by God that we will stand against you in the streets, we will enter your houses and we will slaughter you just like sheep," the clerics said in a statement.
A senior aide to firebrand Shiite cleric Muqtada al-Sadr urged Iraqi forces not to fight alongside U.S. troops.
"We appeal to the Iraqi National Guard and Iraqi police not to help the occupation troops as they want to target the Iraqi people in Fallujah," said Sheikh Abdul-Hadi al-Daraji. The Iraqi troops should not be a tool in the hands of the occupation troops."
In the first foray across the river into Fallujah proper, Marines on Monday morning secured an apartment building in the city's northwest corner, said Capt. Brian Heatherman, of the 3rd Battalion 1st Marine Regiment.
He said there were some Iraqi casualties as the troops seized the building, where Marines found an improvised bomb hanging above a doorway — one of the many variety of booby traps they expect to come across in the urban battle.
U.S. and Iraqi commanders have vowed to stamp out Sunni Muslim guerrillas controlling Fallujah and other cities north and west of Baghdad ahead of vital January elections.
Allawi said emergency measures would be imposed on Fallujah and Ramadi, another insurgent stronghold nearby, beginning at 6 p.m. Roads and government facilities in the two cities will be closed, all weapons will be banned, Iraq's borders with Syria and Jordan will be closed and Baghdad's international airport will be shut down for 48 hours.
Allawi's government announced Sunday that it was imposing a 60-day state of emergency across Iraq — except for the Kurdish-run north.
CBS News Correspondent Kimberly Dozier reports, Allawi has declared a curfew in Fallujah and Ramadi. Iraqi officials say this is the first major salvo in their campaign to end Iraq's terrorism problem once and for all.