The search for a 5-year-old Arizona boy who went missing from a campsite north of the Grand Canyon entered its fifth day as volunteers walked shoulder to shoulder in thick vegetation looking for any sign of the child.

An estimated 200 people participated in the search Monday for Jerald Joseph Williams, who wandered off from the campsite while chasing grasshoppers. He was with a group of about 20 people at the site about 12 miles south of Jacob Lake in the Kaibab National Forest.

No signs of the Colorado City boy have been found, but searchers are working under the assumption that he is still alive, said Gerry Blair, a spokesman for the Coconino County Sheriff's Office.

The search has been aided by military helicopters equipped with night vision equipment, ground crews with dogs and ATVs, and numerous volunteers from Williams' hometown. Some volunteers searching thick vegetation have gotten down on their hands and knees looking for clues.

Blair said no signs of an abduction or foul play have surfaced. He said the child's parents are devastated.

"I don't think the mother has left the command post," Blair said. "She had been there the whole time. The father is very involved," Blair said.