KANDAHAR, Afghanistan - With grenades and volleys of automatic fire, Afghan troops and U.S. soldiers wearing "I Love New York" buttons and Yankees caps stormed a hospital yesterday and killed six al-Qaida fighters who had been holed up there for two months.

U.S. and Afghan troops surrounded Kandahar's Mir Wais Hospital before dawn and traded fire with the Arab fighters inside for hours until - just after the noon call to Islamic prayers - American troops barked, "Stand clear!" and they and the Afghans hurled grenades through the hospital windows to launch a final assault.

A series of 20 explosions sent out showers of glass from the hospital, already burning from the morning's fighting, and the pop-pops of pistol shots and rattle of automatic weapon fire followed as troops went in.

Afghan and American forces said all six Arabs holed up in a second-floor ward were killed. There were no American deaths or injuries, and none of the Afghans fighting alongside were killed.

Some injured Afghan fighters were treated at the U.S. military base in Kandahar, said Maj. Mike Gibler, an operations officer for the 101st Airborne Division. He did not know their number or condition.

"These Arabs fought to the death," said a U.S. soldier involved in the hospital siege who identified himself only as Maj. Chris. He described the battle as "a very hard gunfight."

At the Pentagon, spokesman Rear Adm. John Stufflebeem said the Afghan fighters had led the final assault. "They were the front force that attacked the wing and met headlong with those al-Qaida members," he said. "We assisted them."

But he said it was not known exactly who killed the gunmen.

"In terms of ... who might have killed whom, that's not being tracked," he said, adding that one of the wounded Afghan fighters was in serious condition.

The dramatic raid ended the long standoff with the al-Qaida gunmen, who had been left at the hospital by their Taliban allies before the Taliban surrendered Kandahar in early December. After tribal Afghan forces took control of the city, the gunmen - who had brought weapons and explosives with them - refused to submit, threatening to kill themselves and others if anyone tried to take them into custody.

In Washington, President Bush welcomed Afghan leader Hamid Karzai, announcing a $50 million installment in U.S. aid to help rebuild war-torn Afghanistan. Bush said the U.S. military would help train an Afghan police force and national military, a decision he called "a significant change of policy" for the United States.

Bush said U.S. troops would work closely with international peacekeepers in Afghanistan but would not join the multinational force, something Karzai had said he would welcome.

Karzai, the first Afghan leader to visit Washington in 39 years, thanked the United States for its role in ousting the former ruling Taliban militia. Karzai again thanked the United States for helping drive the Taliban out of Afghanistan.

"Afghanistan is a good partner. It will stay a good partner," he said.

The attack at Mir Wais Hospital began when Afghan authorities issued an ultimatum to the al-Qaida fighters to surrender at around 3:40 a.m. as U.S. and Afghan troops moved into place around the facility. The gunmen refused the ultimatum and there was a burst of gunfire and loud explosions. The Associated Press witnessed the morning's standoff and the final assault from a rooftop.

"Early in the morning, the American soldiers came," said Najabullah, an Afghan commander. "The Arabs saw them, and they started fighting." He said the gunmen had thrown grenades. A fire broke out, and black smoke poured from the hospital wing.

Special forces troops, heavily armed and with the antennas of back-mounted satellite phones dangling over their heads, took up positions with the Afghans. Sharpshooters crouched in crannies of the walled compound and crept along the ledge of the second-floor ward where the al-Qaida men were holed up.

U.S. and Afghan troops manned concertina barricades blocking off the streets leading to the hospital. Afghan troops also tried to clear journalists from nearby rooftops, saying they were acting on requests by the Americans.

After the noon call to prayer, the final assault was launched. Most of the U.S. troops wore "I Love New York" buttons and New York Yankees caps in homage to the Sept. 11 terror attack on the World Trade Center towers.

"Up to the last minute, we told every man to surrender," Chris, the special forces officer, said. "But none of them listened."

Afghan commanders said three of the Arabs were killed by grenades and three others in the assault, some of them hiding under beds. Afghan commander Lali Saliki, who was among those who stormed the ward, said he saw one surviving fighter groping for a gun and shot him.

In the aftermath of the battle, the bloodied ward was littered with limbs blown off by the grenades, with bodies under a bed and laying about the floor. Pale, thin fighters lay dead, in sweaters and uniforms. Mattresses appeared soaked in blood.

Chris said the Americans acted only as advisers, but figures in the jackets and khakis worn by special forces were visible in the thick of the action. An Associated Press reporter saw at least one throwing explosives.

The al-Qaida fighters were the last of 10 or so wounded and ill fighters who barricaded themselves in the hospital. On Jan. 8, one fighter tried to escape and blew himself up with a grenade as Afghan guards surrounded him. Two other men were also said to have escaped, but that was never confirmed.

In December, two gunmen were captured when soldiers used the only doctor the men trusted to trick them. The gunmen were handed over to U.S. forces.

Meanwhile, a delegation of distraught villagers trekked to Kandahar to complain to Afghan authorities Sunday that U.S. special forces killed innocent people in a nighttime raid four days earlier.

Stufflebeem said the military had seen suspicious activity at the site north of Kandahar. "This had the clear indications of being a legitimate military target," he said.

U.S. forces entered the site to determine who was using it but came under fire, Stufflebeem said. When the troops defended themselves, they killed 5 to 16 fighters and captured 27 others. They also uncovered a large ammunition dump and warplanes were called in to destroy it, he said.

But the leaders from the remote town of Khas Uruzgan claimed U.S. forces made a mistake, bombing their town hall and clinic and killing and arresting men loyal to Karzai who were collecting weapons for the new government at the compound.