As the U.S. continued air strikes near the Afghan city of Kandahar  Saturday, defense officials disputed reports that the Taliban had shot down a U.S. helicopter — killing two Americans — during an overnight ground raid.

Gen. Richard Myers, chairman of the joint chiefs of staff, said Saturday that U.S. special forces "attacked and destroyed targets" in Afghanistan — including a garrison where Taliban leader Mullah Mohammed Omar had lived in the command and control building.

Calling the mission "successful," Myers said the U.S. commando forces encountered and destroyed stores of rocket propelled grenades, machine guns and ammunition, and carried out their mission "without significant interference from Taliban forces."

He dismissed as "absolutely false" the Taliban's claim that they shot down a U.S. Blackhawk helicopter that crashed near Pakistan's Dalbandin air base in southwestern Pakistan, about 50 miles from the Afghan border.

"It's pretty well established that the Taliban lie," said Myers.

The crash of the helicopter — which was prepared for search and rescue duty — produced the first casualties among U.S. military forces in the two-week-old campaign.

In addition to the two deaths, Pentagon officials said at least two people aboard the chopper were injured in the accident. They declined to say whether there were any American casualties in the commando raid.

The commandos left Afghan airspace by helicopter and returned to base after several hours inside the country, said a defense official who spoke on condition of anonymity. The strike took place near the Taliban spiritual capital of Kandahar.

Summarizing Friday night's raid, in which U.S. special forces consisting of 100 Army rangers launched the first U.S. ground attack in Afghanistan, Myers said the operation's two major objectives were the airfield and a Taliban command and control facility near Kandahar.

He said the operation also was intended to gather intelligence and that the military was evaluating it.

"We met resistance at both objectives," Myers said. "I guess you would characterize it as light."

Myers declined to say whether the special forces foray marked the start of the ground war.

He said some U.S. military missions in Afghanistan are "visible" and others are "invisible."

Myers said 100 planes struck 15 planned target areas including anti-aircraft sites. The U.S. also flew four C-17 humanitarian missions, dropping 68,000 rations for a total to date of 575,000 in western Afghanistan and northern alliance territory.

"We are destroying terrorist hideaways. We are slowly but surely encircling the terrorists so that we can bring them to justice," President Bush said from an economic summit in Shanghai, China. He said he grieved for the dead soldiers, who "died in a cause that is just and right."

Refusing to comment on the raid itself, Bush said, "I am satisfied we are making very good progress."

Conflicting Reports

Taliban officials had claimed Saturday to have driven U.S. forces out of their targets; that the command facility had been vacated before the attack because of the United States’ relentless, 13-day bombing campaign; and that Taliban fighters had shot down the Black Hawke helicopter.

"It was hit inside Afghanistan and landed in Pakistan just across the border," said Sohail Shaeen, spokesman for the Taliban embassy in Islamabad. "The United States is calling it an accident because they don't want to hurt their morale of their troops."

A Taliban spokesman, Amir Khan Muttaqi, told al-Jazeera TV of Qatar that Taliban fighters drove off the Americans.

"I can say that this commandos attack has failed," he said. "I think we hit one of the helicopters, but I am not sure. The important thing is that they faced defeat. Their plans have failed and God willing all their aggressive planes will fail."

Dismissing these reports, Myer said Saturday that the helicopter was attempting to land when dust or debris kicked up by the rotating blades caused the pilot to lose control. The exact cause was still under investigation.

The Taliban's official news agency, Bakhtar, said four U.S. helicopters landed at Kohi Baba, a mountain region northwest of Kandahar. The area, which had been pounded by U.S. bombs, was empty, the news agency reported. It said that U.S. special forces left without encountering Taliban soldiers.

But Noor Mohammed, an Afghan refugee arriving in Pakistan, said the raid occurred at Qila Jadeed, a Taliban garrison about 20 miles northwest of Kandahar. He said 25 Taliban fighters were killed.

Myers also confirmed that the U.S. troops had inflicted Taliban casualties.

Meanwhile, in an interview published by the Pakistani newspaper The News, Mullah Jalaluddin Haqqani — a veteran of Afghan’s ten-year struggle against the Soviet Union—said Americans were "creatures of comfort" who could not survive the rough Afghan winter just ahead.

"We are eagerly awaiting the American troops to land on our soil, where we will deal with them in our own way," Haqqani was quoted as saying. "The Americans will not be able to sustain the harsh conditions that await them."

The U.S. continued air attacks Saturday, striking with dozens of Navy strike fighters, several Air Force bombers and a few Air Force F-15E fighter-bombers, Myers said.  The Air Force's AC-130U gunship, which was in action earlier this week, including during Friday night's U.S. Army commando raid, was not scheduled for missions Saturday, said the official, who spoke on condition of anonymity.

In preparation for ground action, the USS Kitty Hawk, an aircraft carrier in the Indian Ocean, was loaded with special forces last weekend.

The United States has stressed that Usama bin Laden's al-Qaeda network and the Taliban are the targets of the campaign, not Afghan civilians. The United States is "trying to be as careful as we possibly could" to avoid civilian casualties, Bush assured Asian leaders at the summit.

Meanwhile, raids in the Kandahar area have sent thousands of Afghans fleeing the Taliban stronghold, the U.N. refugee agency said.

Afghanistan's neighbors, already hosting millions of Afghans from two decades of previous conflict, have sealed its borders -- fearing influxes of fleeing civilians and fighters.

Pakistan again closed its borders Saturday after about 3,000 Afghans entered the country Friday — the largest total in a single day since the current crisis began.

The U.N. High Commissioner for Refugees, Ruud Lubbers, said the number of Afghans in flight was surging.

"Hundreds of thousands ... are on the roads," Lubbers told a briefing at the United Nations in New York.

U.N. refugee agency officials say up to 80 percent of the roughly half-million residents of Kandahar have fled.

U.N. refugee agency Fatumata Kaba said refugees speak of widespread looting and desperate struggles for food. "What the new arrivals tell us is that yes, law and order is breaking down," Kaba said.

The Associated Press contributed to this report.