The C-130 "Hercules" crashed at Jalalabad Airfield on Friday shortly after midnight local time.

Initial indications suggest the crash was an accident, according to the US Air Force, which has launched an investigation.

The soldiers and contractors were part of operation "Resolute Support," the NATO-led training and support mission for Afghan security forces. The US maintains about 10,000 troops in the country after ending formal military operations last year.

The latest available numbers provided by the Pentagon, released in July, show there are also some 29,000 contractors, 10,000 of which are US citizens.

The crash came as Afghan forces said they retook control of the strategic northern city of Kunduz on Thursday, three days after Taliban militants stormed the city and pushed out government forces.

US and NATO special forces and airstrikes were involved in the operation to retake the city.

cw/sms (AFP, AP, dpa, Reuters)