Up to 15,000 US and Iraqi troops have launched a massive assault on Fallujah in a bid to end to six months of rebel control of the Iraqi city.
In an attack code-named Operation Phantom Fury, US artillery, tanks and warplanes pounded the district's northern edge, in an attempt to soften the defences and to set off any bombs and boobytraps before troops moved in.
At the same time, another force of 4,000 troops pushed into the north-eastern Askari district, the first large-scale assault into the insurgent-held area of the city, the US military said.
Earlier, US tanks and infantry took control of the city's main hospital and two bridges over the Euphrates River and attacked the city's main railway station amid reports that up to 42 rebels had been killed.
We have no other option but to take the necessary measures to protect Iraqi people from these killers and liberate FallujahIyad Allawi
Iraqi Prime minister Mr Iyad Allawi announced the emergency measures would be imposed in Fallujah and the other stronghold town of Ramadi beginning tonight. He said a curfew would begin at 6 p.m. (3 p.m. Irish time).
At a Baghdad press conference today, he said Iraq's borders with Syria and Jordan will also be closed off and Baghdad's international airport would be shut down for 48 hours.
"Once again, we have seen more criminal acts committed by these terrorists who continue to use Fallujah as a base for their operations. We have no other option but to take the necessary measures to protect Iraqi people from these killers and liberate Fallujah," he said.
Mr Allawi said that during the opening of today's offensive, troops "entered Fallujah Hospital, capturing four foreigners and killing 38 persons. We do not know whether they are Iraqis or not. They were stationed in the hospital in order to carry out terrorist actions."
Two of the foreign "terrorists" seized were from Morocco, he said.
US troops earlier shelled Fallujah and entered the western suburbs of Fallujah. There are estimated to be some 6,000 rebel fighters in the city.
The US military has reported its first casualties of the offensive - two marines were killed when their bulldozer turned over into the Eurphrates River.
An AC-130 gunship struck Fallujah with cannon fire and machineguns and a heavy bomb dropped in the northwest sent up a column of smoke. Smoke also billowed from a western area.
Heavy fighting erupted on the city's eastern and western fringes, including near bridges over the Euphrates.
Inside the city, masked guerrillas moved through empty streets with assault rifles and rocket-propelled grenades. Television footage showed one man in the western Jolan district firing a grenade launcher at an unidentified target.
Guerrillas in other Iraqi cities and towns have recently increased attacks, killing at least 60 people in weekend violence that mostly targeted the security forces.
US forces have
gathered on two sides of the city where the military says 1,000 to 6,000 fighters are.