The fiery crash of a military helicopter in bad weather was the deadliest incident for Americans in Afghanistan (search) since the fall of the Taliban (search) in 2001, the U.S. military said Thursday, identifying 13 of the 16 victims as American service personnel.

The nonmilitary victims in Wednesday's crash were U.S. government contractors, officials said. Their nationalities weren't released. Two other U.S. soldiers were missing. The names of the victims were withheld pending notification of next of kin.

The CH-47 Chinook (search) went down near Ghazni city, 80 miles southwest of the capital, Kabul, as it returned to the main U.S. base at Bagram from a mission in the insurgent-plagued south.

"Recovery work at the crash site will resume upon the arrival of a mortuary affairs team," U.S. military spokeswoman Lt. Cindy Moore said. With the weather still bad, the team was traveling to Ghazni by road, she said.

Moore said the transport helicopter was returning from its mission when controllers lost radio contact. A second Chinook made it safely back to the sprawling base north of Kabul.

Afghan President Hamid Karzai (search), frequently flown around the country in U.S. military helicopters to protect him from assassination, expressed his condolences.

"I deeply deplore this incident, which took the lives of people contributing to stability and security in Afghanistan," Karzai said in an e-mailed statement.

Afghan officials said the helicopter plunged into a patch of flat desert three miles outside the city and burst into flames. The wreckage was strewn over open ground near a brick factory.

Abdul Rahman Sarjang, Ghazni's police chief, said his men and U.S. troops were guarding the crash site on Thursday while other American soldiers collected parts of the helicopter.

He said more than a dozen bodies, some badly burned, had been taken to a small American base nearby. The thick clouds and strong wind that may have contributed to the crash were preventing U.S. helicopters from flying the remains to Bagram, he said.

Sarjang said witnesses reported one of the helicopter's two rotors looked damaged before it hit the ground. He said he saw no sign of enemy fire, and militants had issued no claim of responsibility by Thursday morning.

According to U.S. government statistics, at least 135 American soldiers have died in and around Afghanistan since Operation Enduring Freedom, the U.S.-led war on terrorism, began after the Sept. 11 attacks in America.

Accidents have proven almost as deadly as attacks from Taliban-led insurgents, including a string of helicopter crashes and explosions caused by mines and munitions left over from the country's long wars.

The previous worst incident in Afghanistan was an accidental explosion at an arms dump in Ghazni province that killed eight American soldiers in January 2004.

Last November, six Americans — three civilian crew members and three U.S. soldiers — died when their plane crashed in the Hindu Kush mountains.

About 17,000 U.S. soldiers are in Afghanistan battling the Taliban and training a new Afghan army.