National Transportation Safety Board investigators Saturday were still probing a plane crash that killed a St. George pilot Thursday afternoon, the Beaver County sheriff's office said.

Shawn Sypherd, 22, died when his single-engine Piper crashed 6 miles south of Milford, while en route from Provo to St. George. The plane carried no passengers.The plane disappeared from Salt Lake air traffic controllers' screens Thursday at 3:26 p.m., and attempts to make radio contact failed.

"There was radio and radar contact up until the time it went down," said Lee Fryer, Seattle Federal Aviation Administration. "We just don't know what happened."

Beaver County sheriff's officers told the FAA that a witness saw the craft crash and a Utah Highway Patrol plane found the wreckage. Witnesses told the sheriff's office that the wings and tail were ripped off the plane as it went into a spin.

"It was scattered for three-quarters of a mile," said Fryer.

There was no indication of a fire. "They will look for mechanical problems and as a normal course they will take a toxicology test on the pilot," Fryer said.