The search for a missing boy has been temporarily called off, the Franklin County Sheriff's department confirmed.

A large "grid" around the neighborhood where 13-year-old William "Ben" Ownby had been covered by searchers and no clues to his whereabouts have been found.

Ben was feared abducted Monday after getting off a school bus near his rural eastern Missouri home. He was last seen around 4:15 p.m. Monday near Missouri Route 50 in Beaufort, an unincorporated town about 60 miles southwest of St. Louis.

An Amber alert was issued Tuesday as the Franklin County Sheriff's Department, the Missouri State Highway Patrol and the FBI were joined by dozens of volunteers in the search.

Ben and a friend got off the bus after attending middle school in nearby Union, then separated. Ben's friend told authorities he looked back minutes later to see a white pickup truck with a camper shell in an apparent hurry, backing into a ditch briefly before speeding away.

Ben's father, William Ownby, said the abduction came "out of the blue," and he couldn't imagine why anyone would be motivated to take his son.

Ownby described Ben as a straight-A student, a Boy Scout who loves to play computer games. He said the boy was dropped off every day at the same bus stop, about 500 feet from their home in a wooded neighborhood.

Searchers fanned out again Tuesday in hilly, wooded areas around Beaufort, some on ATVs, some on horses, most on foot.

"Everybody's willing to help," Beaufort Fire Chief William Borgmann said. "Everybody wants to do something."

Ben is white, 4-foot-10 and weighs about 100 pounds. He was last seen wearing a hooded St. Louis Rams windbreaker and blue jeans.

Sheriff Gary Toelke asked that residents in the region keep an eye out for the white pickup. It had the word "Nissan" written in black letters on the back, but authorities weren't certain it was a Nissan.

Toelke described the pickup as beat-up. It had dents and rust and lacked hub caps. The camper shell had one continuous window along the sides, with what appeared to be a ladder rack on top.

"The public is going to be very important in solving this because somebody has seen that truck," Toelke said. "Somebody knows where it is."

He also said the boy was carrying a black backpack that may have been discarded along a road.