As U.S. troops poured from the belly of a Chinook helicopter, a rocket-propelled grenade fired by the Al Qaeda hit the craft and American forces scurried back aboard and took off. A head count showed someone was missing.

For the Americans, their worst fears came true on Monday.

The missing serviceman was captured and killed by Al Qaeda. "We saw him on the Predator being dragged off by three Al Qaeda men," said Maj. Gen. Frank L. Hagenbeck, referring to an unmanned reconnaissance plane mounted with a real-time video camera.

The helicopter managed to fly a few miles before it was forced to put down again because of mechanical problems.

"Another helicopter flew in to rescue the downed aircraft, and that helicopter included a Quick Reaction Force of about 30 special operations troops," said Hagenbeck, the operation commander.

Pentagon officials identified the dead serviceman as Petty Officer 1st class Neil C. Roberts, 32, of Woodland, Calif. Roberts was based in Norfolk, Va., with a Navy SEAL unit.

A Pentagon account by Marine Maj. Ralph Mills said Roberts died of a bullet wound after surviving a fall from the helicopter.

Brig Gen. John W. Rosa, deputy director of operations for the Joint Chiefs of Staff, told a Pentagon briefing that a U.S. rescue team recovered the man's body.

Despite initial setbacks several hundred Taliban and Al Qaeda fighters were killed Tuesday by Apache attack helicopters and Air Force fighters, Hagenbeck said.

"On Tuesday we caught several hundred of them with RPGs and mortars heading toward the fight. We body slammed them today and killed hundreds of those guys," the commander said.

U.S. and Afghan forces met far stiffer resistance than expected in the mission to wipe out Taliban and Al Qaeda troops holed up the mountains and caves in the Gardez region about 75 miles south of Kabul, commanders and soldiers said.

"I don't think we knew what we were getting into this time, but I think were beginning to adjust," said Sgt. Maj. Mark Nielsen, 48, from Indianapolis.

Roberts and at least seven other Americans have died in the fighting since Saturday and about 40 have been wounded. Six others died in the operation after they were being put down for battle by CH-47 Chinook helicopters.

The operation, code-named Anaconda, had originally called for a small detachment of U.S. special forces to work with Zia Lodin, a local Afghan commander, to enter the town of Sirkankel to flush out suspected Al Qaeda and foreign Taliban forces. Sirkankel is about 25 miles south of Gardez.

But many U.S. and Afghan troops were pinned down for hours by the unexpectedly stiff resistance from the Taliban and Al Qaeda.

Early on the operation ran into problems. Zia was unable to enter Sirkankel on Saturday when his force of up to 450 men were caught in a mortar barrage. Two men were killed and 24 wounded. A U.S. special operations soldier was also killed in the operation and two more were wounded.

Elements of the 10th Mountain Division were pinned down Saturday after taking fire from the town of Marzak. Lt. Col. Frank LaCamera and a force of about 40 soldiers were caught in a 12-hour battle. Mortar rounds and rocket-propelled grenades landed as close as 15 yards to their position and 13 American soldiers were wounded.

All the U.S. Apache helicopters flying air support during the first day of the battle were damaged. Several took direct hits from RPGs, but all of them were able to return to base.

Also on Saturday, Col. Frank Wiercinski, a brigade commander for the 101st Airborne, landed on a ridge to the south of Sirkankel to monitor the progress of the operation. Soon after landing, Wiercinski's detachment of about 11 men were attacked and pinned down.

"We survived three mortar barrages during the day and at one point we had between 9-10 Al Qaeda coming to do us," he said. "But instead, we did them."

Nielsen's detachment took fire for several minutes after the helicopters dropped them off. Soldiers began taking fire from an Al Qaeda military compound about 200 yards from where they had landed.

The troops eventually entered the compound, about a half-mile from Sirkankel, and found several 57 mm recoilless rifles, an 82 mm mortar and documents.

"It was unbelievable, in the mud hut where these guys slept, the beds were still warm and tea was still brewing," Nielsen said. "We also found lots of AK-47 ammunition and medicine along with night vision devices and radios. We destroyed most of what we found."

The seized documents that were taken included an electronics book, a state identification card from Saudi Arabia, address book, a Koran and various business cards and receipts. One of those receipts was from a hotel in Mashhad, Iran, near the Afghan border.

"The enemy decided to stay and the call has gone out for Jihad (holy war), Nielsen said.

He said Taliban and Al Qaeda forces had been detected moving toward the battle from the Khost area in southern Afghanistan and along trails leading from Pakistan. He said small groups of fighters totaling 700 to 800 men had joined the fight.

U.S. officials said the operation around Gardez, a shift in American tactics, has drawn masses of Taliban and Al Qaeda forces out of hiding and into combat.

"I wouldn't call this the coup de grace, but its a very large operation which could show our resolve for going after even larger targets," Wiercinski said.