US Marines are reported to be fighting Iraqi forces, including tanks, on the southern outskirts of Saddam Hussein's home town of Tikrit today.
"It's a very, very significant attack. They've brought forward a great number of Cobra assault helicopters and there are Marine F-18s (aircraft) overhead," one reporter said in a live telephone call from Tikrit.
He said Marines had also fought Iraqi troops in the area earlier in the day.
"There were two significant battles...this morning. Iraqi infantry came out of their holes to fight the Marines in their light armoured vehicles. About 15 Iraqis died in that exchange, no Americans," he said.
"Aircraft hit five Iraqi tanks which were on the move."
Earlier today, the US general in charge of the war said American forces were meeting no resistance in Tikrit.
General Tommy Franks, who has orchestrated the US-led invasion, said troops marching on Tikrit had met little resistance, but warned that some fighting remained to be done.
"I wouldn't say it's over, but I will say we have American forces in Tikrit right now," General Franks told reporters from Central Command headquarters in Qatar.
During their push towards Saddam's northern powerbase, the last major centre yet to fall to the invaders, US troops rescued seven missing US POWs, all of whom appeared in relatively good health.
As the US troops reached Tikrit, life appeared to be returning to normal in Baghdad and the northern oil hub of Kirkuk after days of looting.
However, tensions between Muslim Shi'ite factions appeared close to boiling point in the holy city of Najaf.
Normality slowly returned to Baghdad today, with street-traders and kiosks selling food and cigarettes for the first time since US troops seized the Iraqi capital.
Thousands of Iraqis who had fled the fighting drove back into the city with furniture and clothes strapped to their cars.
Some looting was still reported but nothing on the previous scale when ministries, shops and a museum were ransacked.
Anxious to restore calm to Baghdad, hundreds of Iraqi police and civil servants responded to US calls to meet in the city centre on Sunday and discuss returning to service. "We want to help the people, not Saddam Hussein," said policeman Abdel Wahed Ahmed.
Saddam himself has gone to ground. Some people believe he may be holed up in Tikrit, others suspect he may have died in an air raid on the Iraqi capital last week.
General Franks said the United States had Saddam's DNA and would use it to check whether attempts to kill him had succeeded.
"He's either dead or he's running alive," General Franks told CNN. "He'll simply be alive until I can confirm he's dead."
As a degree of order returned to a number of areas, religious tensions flared in Najaf between Shi'ite factions. An aide to a top Shi'ite cleric said an armed radical group had surrounded his house and had given him 48 hours to leave.
"Armed thugs and hooligans have had the house of (Grand) Ayatollah (Ali) Sistani under siege since yesterday," said Ayatollah Abulqasim Dibaji. "Total terror reigns in Najaf."
A mob hacked to death two Shi'ite clerics in the city last week. Aware of sensitivities in the holy centre, US troops have kept their distance in the city, but they will want to prevent any major infighting between Shi'ite groups.
Shi'ites make up 60 per cent of Iraq's population of around 26 million but have been persecuted for decades by Saddam's secular Sunni-dominated Baath Party.
US generals had suggested that the remnants of the Iraqi army and Baath party leaders might mount a last stand in Tikrit.
However, television pictures showed dozens of abandoned tanks and armoured vehicles on the outskirts of the town, suggesting that the defending forces had fled.
Two CNN vehicles briefly entered the town. When they tried to leave, shooting erupted and the cars ran a checkpoint, with a CNN security adviser firing from his machinegun.