Three others killed in Wednesday's crash were US government contractors, Lieutenant Cindy Moore said on Thursday.
Their nationalities were not released. Two more US soldiers were missing. The names of the victims were withheld pending notification of next of kin.
The CH-47 Chinook went down in bad weather near Ghazni city, 130km southwest of the capital, Kabul, as it returned to the main US base at Bagram from a mission in the south.
"Recovery work at the crash site will resume upon the arrival of a mortuary affairs team," Moore said.
Loss of contact
Moore said the transport helicopter was returning from a routine mission on Wednesday afternoon when controllers lost radio contact. A second Chinook made it safely back to the sprawling base north of Kabul.
Afghan officials said the helicopter plunged into a patch of flat desert 5km outside the city and burst into flames. The wreckage was strewn over open ground near a brick factory.
The helicopter was returning from
a routine mission
Abdul Rahman Sarjang, the chief of police of Ghazni, said his men and US 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 of them badly burned, had been taken to a small American base nearby.
The thick cloud and strong winds that may have contributed to the crash were preventing US helicopters from flying the remains to Bagram, he said.
He said he saw no sign of enemy fire, and fighters had issued no claim of responsibility by Thursday morning.
According to US government statistics, at least 135 American soldiers have died in and around Afghanistan since the US-led "war on terrorism" began after the 11 September 2001, attacks in the US.
Accidents have proven almost as deadly as attacks from Taliban-led fighters, including a series of helicopter crashes and explosions caused by mines and munitions left over from the country's long wars.