Authorities investigate a Fresno County pipe bomb explosion

May 1, 2013 12:30:21 AM PDT
An investigation is underway after a pipe bomb went off near Northwest Fresno.

The device exploded inside a mailbox in the area of Glenn near Gettysburg around 10:30 p.m. Tuesday.

The Fresno County Sheriff's Office says no one was hurt and it's unclear why that particular mailbox was targeted. Authorities say no other devices have been found in the area.