DAVISON TOWNSHIP, Mich. (AP) — Authorities are stepping up efforts to search for a 9-year-old boy reported missing following a gathering at a Flint-area park.

Hundreds of law enforcement officials are on hand for Wednesday’s searches after rain hampered efforts a day earlier.

Authorities say Omarion Humphrey has been missing since Saturday evening from Lake Callis Recreation Complex in Genesee County’s Davison Township. An Amber Alert was issued for the child, who authorities say is severely autistic and may not speak but answers to the name “Mars.”

The Flint Journal reports searches are planned in a five-mile radius.

Khisha Humphrey says her son was with a foster family. She says he’s previously hid but believes he was abducted.

Police Chief Rick Freeman says he’s not ruling out any possibilities. A $2,500 reward is being offered.