DAVISON TWP, MI -- An Amber Alert has been issued for 9-year-old Omarion Humphrey, a boy with autism who went missing Saturday, July 4, at the Lake Callis Recreation Complex in Davison Township.

Davison Township Police Chief Rick Freeman said the alert was issued Sunday morning, July 5, due to the boy's medical condition and the amount of time he's been missing.

"We have no reason to believe, at this point, that he's been abducted," Freeman said.

"The Amber Alert has very strict rules on when you can and cannot initiate," with the worst-case scenario being a child abduction, Freeman said. His commanding officers kept in touch with officials and, "Because of the autism and because of the evolving time here, and the immensity of this search they allowed us to trigger the Amber Alert."

Omarion went missing around 6 p.m. Saturday from Lake Callis, on Gale Road, between Davison Road and Court Street. Freeman said dog teams have searched the creek in the area. The Genesee County Dive Team is also searching small ponds in the area and going back over Lake Callis.

The boy has been described as 4-feet-tall, 70 pounds and last seen wearing no shirt, no shoes and black shorts with a red stripe. Omarion is severely autistic and cannot speak, but he answers to "Mars," police said.

Freeman said the search has expanded to "several miles, as far as our radius is concerned," with a mix of professional and volunteer searchers.

"It's overwhelming how outstanding the support has been," said Freeman. Two Salvation Army vehicles were at the scene to provide food and drink to search teams.

Anyone with information on Omarion's whereabouts has been asked to call 810-732-9911 or 911.