US army troops are fighting street by street battles with Iraqi paramilitaries in the central city of Kerbala in an attack aimed at protecting the rear of US forces moving into Baghdad.
Iraqi fighters took up positions on rooftops in the narrow streets of this Shi'ite shrine city on Saturday and opened fire with rocket propelled grenades and assault rifles. US planes and troops hit back with laser-guided bombs, artillery and heavy arms fire.
"It's freaky in there. Lots of bullets flying around. It's pretty scary," said one young US soldier who was evacuated after being hit by fragments from a hand grenade.
The attack on Kerbala came as advance US forces pushed into Baghdad, 110 km (70 miles) to the north, on the 17th day of a war to overthrow President Saddam Hussein.
It followed a similar US sweep two days earlier through Najaf, another holy Shi'ite Muslim city in central Iraq, to root out paramilitaries and other fighters loyal to Saddam who could threaten long US supply lines stretching up from the south.
Troops from the "Screaming Eagles" 101st Airborne Division landed in helicopters on the western edge of Kerbala, moving in beside a tank battalion with Apache attack helicopters overhead.
Iraqis offered tough resistance from one building complex, keeping OH-58 Kiowa Warrior reconnaissance helicopters at bay with sustained fire whenever they closed in. At least two US soldiers were wounded in the fighting.
A Reuters correspondent, within sight of the golden-domed mosques in the city centre, reported he heard several loud explosions and a heavy pounding of artillery.
Air Force officers said fighter planes had hit a Republican Guards facility, the city headquarters of the ruling Baath Party, and an ammunitions depot with 2,000 pound bombs shortly before midday (0800 GMT).
Three huge plumes of smoke rose above the city and one of the bombs appeared to spark a series of secondary explosions.
A US officer told Gray the strike against Kerbala came from four different directions.
"We are here to reduce the resistance in the town (and) to allow things to return to normal in Kerbala," said Major Eric Wick, second in command of the 2nd Battalion of the 70th Armoured Regiment. He said the mission would help secure supply lines and allow humanitarian deliveries to Kerbala.
US sources said they believed hundreds of Fedayeen paramilitaries could be based in Kerbala, threatening US lines stretching hundreds of kilometres (miles) from Kuwait.
Lieutenant-Colonel Chris Holden said US forces could not remain in Baghdad for the long term until they had secured the cities to the south of the capital.
"It would have to be raids and destruction missions, but it couldn't be long-term effective as long as Kerbala and other towns can serve as a Fedayeen base to attack our forces," said Holden, a battalion commander of the 101st Airborne.
Najaf and Kerbala, home to the holiest Shi'ite shrines in Iraq, rose up against Baghdad after Iraqi troops were repulsed from Kuwait by U.S.-led forces in 1991. Forces loyal to Saddam put down the uprising within weeks.
One US officer said Najaf residents were welcoming the US forces and offering to help them.
US 70th Armoured Regiment forces said they found 1,000 mortar rounds in a hospital on Kerbala's northern outskirts and came across an abandoned air defence system.
They also said they killed six Iraqis in a gunfight which broke out when some of them had reached for weapons hidden in a tractor-drawn cart. Gray said he saw several bodies lying by the tractor, which still had its engine running as he passed it.