MESA COUNTY, Colo. -

A small airplane that went missing Thursday in Mesa County has been found. The sheriff's office says all three people on board, a pilot and two passengers, were killed.

The plane was found around 9:30 Thursday night in Porter Creek, east of Collbran.

The plane was reported overdue on its scheduled return to the Mesa Mack Airport on Thursday evening. Its route and destination are unknown.

The aircraft's Emergency Locator Transmitter beacon was activated. The Civil Air Patrol and the High-Altitude Army National Guard helped with the search from the air. Mesa County Search and Rescue Snow Skippers responded to the crash site once the plane was found.

The cause of the crash is unknown at this time. The sheriff's office says it expects the FAA to investigate the crash. Recovery efforts are expected to last all day.