US forces are fighting Iraqi troops on the outskirts of the key Iraqi town of Tikrit, the hometown of ousted Iraqi President Saddam Hussein and the last stronghold of his regime.
Reports said sounds of fierce fighting were heard on the edges of the town. A Canadian journalist reports the Americans launched their attack Sunday evening and that a number of tanks and helicopters are being used.
Earlier, the commander of coalition forces in Iraq said US Marines operating around Tikrit found alive seven US prisoners of war.
US Defense Secretary Donald Rumsfeld said two of the troops have gunshot wounds. The soldiers, one of whom is an African-American woman, are being flown to Kuwait.
Relatives of the soldiers said they had received official notification the former prisoners were safe. Some identified their loved ones from television footage.
US Marines found the Americans while moving from Baghdad to Tikrit. President Bush hailed the rescue of the seven soldiers, calling it a great day.
First live images broadcast by C-N-N showed abandoned armored vehicles along a highway leading into Tikrit, along with deserted military bases, and no sign of Iraqi troops.
A C-N-N news crew heading into Tikrit was stopped by gunmen and ordered to turn around, and later came under machine-gun fire while leaving the city.
C-N-N reporter Brent Sadler and his crew escaped unharmed. Two people in the convoy accompanying them reportedly were injured.
In northern Iraq, US troops have moved into Mosul and Kirkuk, which Iraqi forces abandoned last week.