Kabul , Afghanistan ( CNN ) -- The bodies of three American contractors who died in a plane crash in Afghanistan earlier this month have been recovered , NATO 's International Security Assistance Force said Tuesday . The C-12 plane went down in the mountains of Nuristan province October 13 , but the military withheld information about it until the recovery operation was complete , ISAF said in a statement . The crew were subcontractors working for Lockheed Martin , the company confirmed . A spokesman named two of them as Jeff Lehner , a former Air Force member working for Sierra Nevada , and Randolph Bergquist , a former Marine working for Avenge . They are not releasing the third name at the family 's request . Thomas Casey of Lockheed Martin confirmed the third victim was the co-pilot and also worked for Avenge . The cause of the crash that killed them is not yet clear , but it is not thought to be enemy action , ISAF said . A helicopter sent to recover the remains October 17 itself made `` a hard landing '' that required the crew to be rescued , ISAF said . The helicopter was stripped of sensitive parts Wednesday and destroyed in place Sunday , ISAF said .
3 contractors killed when plane went down in mountains of Nuristan province . Plane , a C-12 , crashed October 13 ; crew worked for Lockheed Martin . Cause of crash not yet clear , but it is not thought to be enemy action . Crew of copter sent to recover remains had to be rescued after hard landing .