But U.S. and British air force officers said coalition warplanes mounting the attacks were in fact coming under heavy fire.

"At the moment we've had no contact with the Iraqi air force but we are receiving significant amounts of ground-to-air fire, both missiles and anti-aircraft," Royal Air Force spokesman Group Captain Jon Fynes said at a briefing in Kuwait.

The 3rd Infantry division, 2nd Brigade -- also known as the Spartans -- covered about 230 miles in 40 hours to take up fighting positions ahead of all U.S. forces, about 100 miles from Baghdad.

"It's going more rapidly than I expected. We're making very, very rapid progress," said U.S. Air Force Major-General Daniel Leaf.

On NBC's Meet the Press Sunday, Defense Secretary Donald Rumsfeld characterized the progress of the five-day-old war as excellent, noting that, "there are periodic instances when the resistance is quite stiff. ... The fact that there is a firefight, someone ought not to be surprised."

Possible Prisoners of War

The Arab satellite station Al-Jazeera aired footage from Iraqi television Sunday of interviews with what the station identified as captured American prisoners, and also showed bodies in uniform in an Iraqi morgue that it said were Americans.

Rumsfeld told CBS that if they are indeed coalition soldiers, "those pictures are a violation of the Geneva Convention."

There was no confirmation that the prisoners were U.S. troops, or if they were, what unit they were attached to. Two of the prisoners identified their unit only as the 507th Maintenance; there is a 507th in both the Army and the Air Force.

In the broadcast, four bodies could be seen lying on the floor of the room.

In the Iraqi television footage, at least five prisoners including one woman were interviewed separately. Two were bandaged. They spoke American-accented English.

British Aircraft Shot Down

A Patriot missile battery shot down a British Royal Air Force fighter aircraft near the Iraq-Kuwait border Sunday, British officials said, although they didn't specify whether the battery was U.S., Kuwaiti or of another country.

The crew is listed as missing.

Rumsfeld said Sunday there had been a report of a missing allied aircraft and that there also may be some captured U.S. soldiers.

In an interview with NBC's Meet the Press, Rumsfeld said he had no information about claims by Iraq that two Western pilots had been forced to abandon their aircraft over Baghdad. But when asked about missing planes, he responded, "There has been a report of an aircraft that's missing."

Baghdad has claimed it is holding Western soldiers prisoner.

U.S. Air Force Gen. Richard Myers, the chairman of the Joint Chiefs of Staff, said Sunday that U.S. authorities were searching for fewer than 10 U.S. soldiers who were unaccounted for in southern Iraq.

On Fox News Sunday, Myers said Central Command was investigating the missing troop reports.

"They are trying to account for the soldiers that are reported missing, and beyond that we don't know," Myers said.
 

The coalition brigade raced day and night across rugged desert in more than 70 tanks and 60 Bradley fighting vehicles. At one point, the soldiers ran into an hours-long firefight, killing 100 Iraqi militiamen who confronted the Americans with machinegun-mounted vehicles. Several other allied units engaged in intensive gun battles Sunday. One soldier from the 3rd Infantry Division was killed in a vehicle accident in southern Iraq, while another soldier was killed and 13 injured in a grenade attack in Kuwait in which a Muslim-American soldier was being held as a suspect.

Members of India Co., 3rd Batt., 7th Marines, 1st Marine Division, engage Iraqi soldiers

The official said that allied forces were engaged in "mopping up operations" in and around the city, as they cleaned out remaining pockets of Iraqi resistance.

Near Basra, Marines saw hundreds of Iraqi men -- apparently soldiers who had taken off their uniforms -- walking along a highway with bundles on their backs past burned-out Iraqi tanks.

One pocket of Iraqi resistance engaged U.S. Marines in Umm Qasr, an important port city that allied forces said Saturday was secured. A dramatic gunfight between U.S. soldiers and up to 120 Iraqi fighters reportedly holed up in a building played out on live television.

The fighting ended before noon Sunday.

Earlier Sunday, Iraqi officials said that 77 civilians had been killed and 503 wounded in coalition air strikes across the country.

Iraqi state television reported fighting between Iraqi ruling Baath party militias and U.S.-British forces near the Shiite holy city of Najaf, 95 miles south of Baghdad. It said the top Baath party official in Najaf was killed.

The U.S. Army took Nasiriyah, a major crossing point over the Euphrates northwest of Basra.

Near the Persian Gulf, Marines seized an Iraqi naval base Sunday morning at Az Zubayr.

Iraqi television reported that Saddam Hussein's home town, Tikrit, had been bombed several times.

Fox News confirmed that the Iraq leader was placed on a stretcher and into an ambulance following the first attacks on Baghdad last week. British intelligence reports backed up that report Sunday.

But Iraqi VP Ramadan denied speculation that Saddam was injured. The official Iraqi News Agency reported that Saddam held a high-level meeting Sunday with top advisers.

"We'll just have to assume that he is alive and well," Rumsfeld said Sunday.

Myers said no weapons of mass destructions had been located thus far, but he voiced certainty that some would be found as the troops advance.