Report: Deadly Afghanistan Helicopter Crash Caused by Insurgent-Fired Grenade

U.S. military investigators say the August Chinook helicopter crash in Afghanistan that killed 30 U.S. troops was caused by an insurgent who fired a rocket-propelled grenade that struck the rear rotor of the aircraft.

It was deadliest single incident for U.S. forces in the decade-long war.

The U.S. Central Command issued an investigation report on the crash on Wednesday.

The report says that after the grenade hit the rotor, the helicopter spun violently and then the main fuselage dropped vertically into a dry creek bed. The copter was immediately engulfed in flames and the fire triggered several explosions of fuel and munitions.

An Afghan interpreter and seven Afghan commandos also died in the Aug. 6 crash in Wardak province.