Fresno County Sheriff's Lt. Victor Wisemer says the unidentified boy was hiking with his family along Highway 180 when he disappeared around 6 p.m. Friday.
Sheriff's officials resumed their search on Saturday. Wisemer tells the Fresno Bee crews are looking for the boy from the air and ground.
But he says steep and treacherous terrain is making the search difficult.
Information from: The Fresno Bee, http://www.fresnobee.com