MOOSE, Wyo. (AP) — The National Transportation Safety Board says the pilot of an experimental plane that crashed Wednesday in grand Teton National Park told air traffic controllers there was a problem with the plane and that the pilot was returning to the airport when the plane crashed.

NTSB investigator Zoë Keliher said Friday the problems with the plane have not been determined.

The victims were identified as Russell Kamtz and Carol Kamtz, of Loveland, Colo. The person piloting the plane has not been identified.

Witnesses reported that the plane dove toward the ground and crashed nose-first.