BROOKSTON, Ind. (AP) — A helicopter pilot from Hawaii who was helping install power lines on new towers died after his aircraft crashed in rural northern Indiana.

Indiana State Police say it isn’t clear what caused Tuesday afternoon’s crash near the White County community of Brookston, about 65 miles northwest of Indianapolis. Workers on the ground attempted to resuscitate the pilot, but he was pronounced dead at the scene by the county coroner.

State police identified the pilot Wednesday as 53-year-old Howard Y. Esterbrook of Kapolei, Hawaii, and said his relatives had been notified.

A preliminary investigation shows Esterbrook was using the helicopter to help Mesa, Arizona-based EC Source install power lines when the aircraft crashed for unknown reasons.

The Federal Aviation Administration and National Transportation Safety Board will conduct an investigation.