Four people were killed when a plane crashed and exploded into flames Saturday after apparently striking power lines in a forested area about 40 miles northwest of the Las Vegas Strip, authorities said.

Federal Aviation Administration spokesman Ian Gregor said a pilot and three passengers were in the single-engine plane that went down about 2:45 p.m. No on survived the crash, he said.

A preliminary investigation shows the Piper Cherokee plane was en route from the North Las Vegas airport to Byron, Calif., when it crashed at the 7,000-foot level of Mt. Charleston's east side, Gregor said.

The plane burst into flames and touched off a wildfire near the Echo Subdivision of the mountain resort area.

Fire officials said the fire quickly climbed the steep and parched terrain of the Spring Mountain Recreation Area and came within a half-mile of homes.

About four hours after the crash, nearly 40 homes were threatened by the 12-acre fire and authorities recommended a voluntary evacuation of the subdivision, said Bureau of Land Management spokeswoman Kirsten Cannon.

The evacuation became mandatory later in the evening. Fire officials expected to fully contain the blaze by 6 p.m. Sunday, Cannon said.

Authorities also closed two major roads leading into the area.

Names of the plane's occupants were not immediately released. No injuries were report.

The crash was under investigation by the FAA and National Transportation Safety Board.