ENGLEWOOD, Colo.  —  A twin-engine cargo plane that vanished from radar before dawn Thursday on approach to Centennial Airport (search) crashed in rugged terrain, killing its pilot, rescue officials said.

Authorities believed only one person was on board, said Becky O'Guin, public information officer for the Parker Fire District (search). The pilot's name was not released.

Airport officials notified emergency crews after losing radar contact with the plane just after 2 a.m. as it was preparing to land.

A crew in a Denver (search) police helicopter found the turboprop Mitsubishi MU-2 east of Interstate 25 in a rural, rugged area in Douglas County, said Becky O'Guin, public information officer for the Parker Fire District. Rescuers were using ATVs to reach the plane.

Heavy rain created muddy conditions that hampered efforts to locate the aircraft.

"The terrain itself is rugged — lots of gullies and shrub oak — but also it's very wet and our air support has very low visibility," O'Guin said.

The aircraft was preparing to land at Centennial Airport when it disappeared from radar, about one to two miles south of the airport.

There was no immediate word on the plane's flight plans or what the plane may have been carrying.