A military helicopter crashed in the Afghan capital Saturday, killing all seven German peacekeepers aboard and two children on the ground. In eastern Afghanistan, attackers killed a U.S. soldier in a gunfight that underscored the dangers coalition forces face in the war on terror.

It was unclear what brought down the Sikorsky CH-53 helicopter in an industrial neighborhood on the eastern edge of Kabul, said Lt. Col. Andreas Steffan, spokesman for Dutch and German peacekeepers. Witnesses said it was not shot down.

In Berlin, the Defense Ministry said the crash would be investigated by German experts. The ministry confirmed seven German peacekeepers died and two Afghan girls were missing.

In Kabul, Police Chief Basir Salangi said the accident killed two Afghan children. The helicopter was on a routine patrol over the city, and crashed in an area where many refugees live.

Late Saturday, members of the 4,800-strong multinational peacekeeping force searched the wreckage and surrounding area for the bodies.

Meanwhile, attackers struck U.S. forces near Afghanistan's mountainous border with Pakistan in two separate assaults, U.S. military spokesman Maj. Steve Clutter said at Bagram Air Base, north of the capital.

An 82nd Airborne Division paratrooper died in a gunbattle in the eastern town of Shkhin. A U.S. Special Forces soldier was wounded in a rocket attack on a U.S. base in the northeastern city of Asadabad.

Joint Chiefs of Staff Chairman Gen. Richard Myers, on a one-day visit to U.S. troops at Bagram, called the American's death "tragic." He said security in Afghanistan was improving -- despite the violence -- but conceded the country's volatile east would likely remain a problem "for some time to come."

It was the first U.S. combat death in Afghanistan since August, and brings to 16 the number of Americans killed in hostile situations here since the war on terror began late last year.

German Chancellor Gerhard Schroeder expressed "deep sorrow" over the helicopter crash, the worst loss of life in recent memory for German soldiers who have taken on increasing peacekeeping duties in the last decade.

"This accident makes it tragically clear . . . that the army's mission in Afghanistan is a difficult and dangerous operation," Schroeder said in a statement.

A witness reported seeing a fire on the helicopter before it went down. Steffan said it clipped the top of an abandoned building -- damaged in the 1990s civil war -- and crashed in a road. Peacekeepers quickly cordoned off the area, scattered with war-ruined factories where refugees now live.

"I looked up and I saw a fire on the helicopter and then it turned onto its left side and crashed in among the buildings," said Mohammed Mousa, a worker in the area. He said it did not appear that the helicopter was fired upon.

The crash came a day after Germany's parliament voted overwhelmingly to extend by a year the mandate of its troops in Afghanistan, doubling the country's contingent to 2,500 to allow Germany and the Netherlands to take command of the force early next year.

The only previous German deaths among peacekeepers in Kabul occurred in March, when two Germans and three Danish soldiers were killed as they disarmed two Soviet-era anti-aircraft missiles.

In Shkhin, American troops were observing a group of "seven to nine individuals" before dawn Saturday when troubles there began, Clutter said.

"They'd had these individuals under observation for a while, they were actually getting ready to approach them to investigate," he said. "As they got closer, they realized they were armed."

The unidentified men fled and opened fire on the American troops. Sgt. Steven Checo, 22, was shot, and died during surgery at a field hospital, according to an Army statement from Fort Bragg, N.C. Checo had been assigned to Delta Company, 2nd Battalion, 504th Parachute Infantry Regiment. The Army said he was from New York but did not specify his hometown.

Clutter said there were no reports of enemy deaths during the gunfight. He said the group escaped into Pakistan.

In a separate incident Friday in Asadabad, also near the Pakistan border, a U.S. special operations soldier was injured when unidentified attackers fired three rockets at a U.S. compound.

The wounded soldier was flown to Bagram and underwent surgery at a U.S. Army hospital. He was in stable condition.

Elsewhere, two rockets were fired on a U.S. base at Khost in eastern Afghanistan late Friday, but no casualties or damage were reported.

Rockets, many Chinese-made and connected to crude timers, are fired almost everyday at U.S. troops in Afghanistan. The rockets are difficult to aim and have rarely caused casualties.

Also Friday, a U.S. soldier participating in a weapons training exercise with Afghan soldiers in the southeastern town of Spinboldak was injured while trying to correct a misfire on a rocket propelled grenade launcher.

Clutter said his condition was stable after undergoing surgery at Bagram.