CORTEZ, Colo. -

Sheriff's officials say a helicopter pilot for a Montana-based company has died after crashing in southwest Colorado.

Dolores County sheriff's officials say the pilot was the only person aboard the helicopter when it crashed Tuesday east of Dove Creek. His name wasn't immediately released. Sheriff's officials say the helicopter was owned by Billings Flying Service in Billings, Mont.

It's not clear what caused the crash. Witnesses reported hearing a loud "pop" and then saw the helicopter plunge. Sheriff's officials say flying debris struck one ground crew member's backpack.

Authorities say the helicopter was helping a subcontractor do seismic exploration for Kinder Morgan. The Cortez Journal reports (http://bit.ly/12EspOK) the helicopter was working with a ground crew to move seismic sensors around to check for oil and gas reserves underground.