FALLUJAH, Nov 11: US troops fought to crush resistance in Fallujah on Thursday, but guerillas hit back with an armed rampage in Mosul and a car bomb that killed 17 people in a crowded Baghdad street.

Marines said they met little opposition in the former guerilla stronghold of Jolan, in northwestern Fallujah, where militants fired only one or two mortar rounds as tanks pushed through alleys. But a huge explosion erupted in the district after dark, sending a fireball into the sky.

And Marines had to call in four air strikes after taking heavy fire at their headquarters in central Fallujah. A marines rifle company had come under continuous fire when it pushed out of the base into the city on a house-to-house search for guerillas.

Jolan, a stronghold for Saddam Hussein loyalists, had seen some of the fiercest fighting of this week's US-led offensive.

"Things are going, I think, as planned. We've got about 70 per cent of the city under control," Gen Richard Myers, chairman of the US Joint Chiefs of Staff, told CBS television. "There have been hundreds and hundreds of insurgents who have been either killed or captured," he said.

But guerillas managed to shoot down two US Cobra helicopters near Fallujah, US military sources cited by Al Arabiya television said on Thursday.

BACKLASH: The Fallujah assault has provoked an upsurge in violence elsewhere in Iraq, as happened in April during an earlier failed attempt to subdue the country's most anti-Western city.