A crudely constructed pipe bomb exploded and disintegrated a mailbox in south Salt Lake County Tuesday night.

Salt Lake County deputy sheriffs said a bomb made of galvanized lead pipe, black powder and detonated by a fuse blew a mailbox apart at 1780 E. Siesta Drive (7480 South) about 10 p.m. Tuesday."The homeowner said he heard a loud `bang,' went outside to investigate but didn't see anything," Salt Lake County Fire Lt. Dennis Steadman said.

The man called the sheriff's office Wednesday morning when he noticed that his mailbox was gone and that another pipe bomb was lying in the street about 5 feet from the mailbox stand.

A Salt Lake County bomb technician was called to the scene and the remaining explosive device was placed in a bomb-proof box and taken to a bunker for analysis.

Steadman said the recovered pipe bomb is about four inches long and one half inch wide.

Deputy sheriffs expect juveniles may have constructed the bombs.

"These type of bombs are more dangerous to the people who build them," Steadman said. "We usually find the culprits because they blow themselves up trying to build the bombs."

He said gunpowder caught in the pipe's threading can ignite when people screw the caps on the pipe ends.

Detectives are dusting the recovered pipe for fingerprints. The bomb builder will face federal charges if they are arrested, Steadman said.