At least 26 security personnel on board a military helicopter were killed on Friday in northwestern of the country when it went down due to technical fault, report said here Friday. The helicopter, reportedly belongs to Pakistan Army, crashed near the Chapar Feroze Khel, a bordering area of Khyber and Orazkzai agencies, report says. According to Inter Services Public Relations (ISPR) the helicopter crashed due to 'technical reasons. However, unconfirmed reports from the areas claim that the helicopter went down when it came under fire by the militants on ground.