At least 11 people, including six U.S. service members, died overnight when a cargo plane crashed while taking off from an airfield in eastern Afghanistan, the U.S. military said Thursday.

The Air Force C-130J, a large turboprop plane used for cargo and transport flights, crashed as it left the airfield in Jalalabad early Friday local time, shortly after midnight, the U.S. Air Forces Central Command said in a statement.

Five civilian contractors working with the U.S. and allied military mission in Afghanistan were among the dead, the statement said. According to media reports, the crash killed two Afghans on the ground, but military officials could not immediately confirm those reports.

Officials said the crash was being investigated but noted that no militant activity had been detected in the area at that time.

Jalalabad is a hub for U.S. and allied military activity in eastern Afghanistan at a time when the international military coalition is winding down its long war in that country. The United States now has about 9,800 troops in Afghanistan and is slated to bring that number to fewer than 1,000 by the time President Obama leaves office in January 2017.

U.S. forces remaining in Afghanistan are now confined mostly to a training and advisory role, although a smaller number of troops conduct limited operations against al-Qaida and other militants.

The crash occurred as Afghan forces, supported by U.S. airstrikes, battle to fully reclaim the northern city of Kunduz from the Taliban. The militants’ seizure of the city this week was a reminder of the threats that Afghanistan’s government faces at a moment when outside military assistance is increasingly limited.