US forces fought suspected paramilitaries loyal to Saddam Hussein in the northern Iraqi city of Mosul tonight and said at least six Iraqis were killed.
Heavy gunfire erupted as night fell on the western side of the Tigris river that splits Mosul down the middle, and US officers said two of their positions in the city came under sustained fire.
In the heaviest fighting in the country for days, US units hit back with heavy machineguns and lit up the night sky with red flares to direct their fire before calling in helicopter gunships.
The shooting subsided after about 45 minutes but US officers said at least six Iraqis were killed, including five, who allegedly opened up with AK-47 assault rifles from in and around a crowd.
The situation was confused by wild gunfire across much of the city, apparently from Saddam supporters marking the toppled president's 66th birthday.
"It was Fedayeen paramilitaries or Ba'ath Party loyalists making a statement against the United States," said Captain J.P. Swoopes of the 101st Airborne Division, which took over control of the city last week.
But another officer said it was possible the initial firing was celebratory and had been mistaken for a coordinated attack on the two Army camps.
Army units had received reports from civilians and intercepted radio communications earlier on Monday that paramilitaries loyal to Saddam Hussein might be preparing an attack.
It appeared to be the heaviest gunfire since US troops first established control in Mosul, Iraq's third largest city, more than two weeks ago.
The city, which lies 390 km (240 miles) north of Baghdad, is divided between Arabs and Kurds. US officers are brokering negotiations on setting up a new local government and also began disarming Kurdish fighters in the city over the weekend.