Iraq's information minister on Friday threatened coalition troops with "non-conventional" attacks -- a "kind of martyrdom operations" -- after allied troops tightened their grip on the area surrounding Baghdad.

And in a tape broadcast on Iraqi television, a man in full military uniform purporting to be Saddam Hussein read a statement calling on Iraqis to strike at coalition forces at the gates of the capital. Saddam, in his statement, referred to the March 23 downing of a U.S. helicopter, which indicates the tape was made after the war began.

• Maps: Iraq | Baghdad

"Perhaps you remember the valiant Iraqi peasant and how he shot down an American Apache with an old weapon," Saddam said. "Hit them with force, resist them, o people of Baghdad, whenever they advance upon your city, and remain true to your principles, your faith and your honor."

Later in the day, Iraqi TV showed video of Saddam being cheered by the city's residents as he walked through bombed-out areas of Baghdad. In one portion of the tape, smoke can be seen rising in the distant sky.

Saddam's only other purported appearances have been in regime-provided videotapes that could have been made before the war began. There has been much speculation that he was killed or wounded in the first air strike of the war, on a bunker in Baghdad on March 20.

So do the tapes prove Saddam is alive?

"Not necessarily," a senior U.S. official told Fox News. "It could. It is the most specific reference to a recent event we have heard."

But the official also noted that "the intelligence community has reached no conclusions" about when the tape was recorded and whether it was after the war began. "It is not proof," he said.

'Martyrdom Operations' Threatened

In the face of the allied juggernaut, Mohammed Saeed al-Sahhaf, Iraq's information minister, sent a threat to coalition forces.

"Tonight we are going to commit untraditional attacks," he said during a press conference Friday. "We will commit a non-conventional act on them, not necessarily military.

"We will do something that will be a great example for these mercenaries."

Al-Sahhaf described the threats as a "kind of martyrdom operations" and insisted Iraq will not use weapons of mass destruction. But he added that the airport, which he described as an "isolated island," will be a "graveyard" for Americans.

Al-Sahhaf's proclamations have been notorious since the war started. He has told the media that the Iraqis have been slaughtering coalition forces and has insisted that Saddam's regime is in full control of Iraq, despite all the reports coming directly from embedded reporters and U.S. military officials that the situation is exactly the opposite.

Baghdad Citizens Flee

Meanwhile, thousands of Iraqis were fleeing Baghdad on Friday as U.S. forces seized the Saddam International Airport on the city's western edge and renamed it Baghdad International Airport. Troops began the dangerous work of exploring its subterranean tunnels for Iraqi defenders under the airport, which lies about 10 miles from the heart of Baghdad.

The first American journalist to be killed in Iraq, Michael Kelly, editor-at-large for The Atlantic Monthly, died Thursday night in a Humvee accident.

A car bomb killed three uniformed personnel at a checkpoint outside Baghdad when a pregnant woman jumped from the vehicle screaming for help.

And U.S. troops at an industrial site found thousands of boxes of white powder, nerve agent antidote, unidentified liquid and Arabic documents on how to engage in chemical warfare. The nerve agent Tabun was also found in what U.S. military officials think was a chemical training site.

Units of the 101st Airborne Division arrived at the newly renamed airport with plans to base its helicopters at the newly seized site.

"We are fighting in urban terrain now, and to be effective, in this terrain you need light infantry forces. This is their forte," said Col. John Peabody of the 3rd Infantry Division.

Armored convoys pressed in from the south. Marines claimed the surrender of 2,500 troops of the now-shredded Republican Guard.

Some told their interrogators they had been told by leaders of Saddam's Baath Party that Americans would burn and pillage Iraq and take no prisoners.

Iraqis fled Baghdad -- which has been cloaked in darkness for more than 24 hours, and headed north to avoid advancing American troops. Vehicles loaded with men, women, children and their possessions clogged exit routes in backups that stretched for miles.

The Baghdad Battle Plan

American commanders were close-mouthed about the next part of the battle plan for Baghdad, but they all said the battle won't be a quick one.

"The fighting is not complete by any stretch of the imagination," Brig. Gen. Vincent Brooks said in a briefing at Central Command. "We don't have any doubts that there will be more fighting ahead … we're not finished with this operation."

Still, units of the 101st Airborne Division arrived at the airport during the day, and Brig. Gen. Vincent Brooks told reporters during a U.S. Central Command briefing Friday that American commandos were already in "key locations" inside the capital.

Special forces can point lasers at targets that laser-guided bombs lock onto and destroy.

Other units are reportedly on the way.

"I could see columns of the U.S. Army and Marines moving forward," said Cmdr. Brian Corey, who flew a bombing mission over Baghdad on Thursday. "That was an impressive sight."

Marines advanced from the southeast, rolling through villages and towns past now familiar sights of discarded Iraqi military uniforms. Crowds sometimes lined the roads, and some Iraqis voiced their hopes in a blend of English and Arabic."

"Thank you. Thank you. Baghdad, Baghdad. Yallah (Go). Yallah," they said.

About 40 miles south of the capital, military barracks were still burning and a metal sculpture of Saddam had been shorn of its head.

Army troops were advancing on Baghdad, as well, and tank units intercepted a battalion of Republican Guard armor about 25 miles outside the city. The Americans called in air cover, and reported the destruction of 10 Iraqi tanks.

"I think we're in a mad dash to destroy as much of their military as possible," said Capt. Chris Carter of Watkinsville, Ga.

U.S. officials suggested an all-out assault might not be their first option.

Gen. Richard Myers, chairman of the Joint Chiefs of Staff, suggested the coalition might isolate members of the old regime in the capital while an "interim administration" is put in place to begin work on a postwar government. A meeting to organize an interim government could be held in Iraq within a week.

Americans backed up their steady ground advances with fresh air strikes on targets in Baghdad and elsewhere in the country of 23 million.

In the north, bombing cleared the way for Kurdish forces to seize a key bridge at Khazer, near the major city of Mosul.

Fox News' Mike Tobin, Jim Angle and Simon Marks and The Associated Press contributed to this report.