FRESNO COUNTY (CBS13) — A helicopter pilot died in a crash while fighting a wildfire in Fresno County Wednesday morning.

Cal Fire officials said the pilot was hired on a Call When Needed (CWN) basis and was assigned to a water-dropping mission on the Hills Fire, south of Coalinga.

After the pilot’s Bell UH-1H helicopter crashed, ground crews responded immediately. The pilot, who was not identified, was the only person in the helicopter during the crash.

Cal Fire said the National Transportation Safety Board (NTSB) started an investigation into the crash Wednesday, with Cal Fire assisting.