Authorities say nearly 900 people are helping search for a 9-year-old Caroline County autistic boy who disappeared over the weekend.

Volunteers hike through woods near North Anna Battlefield Park in Hanover County, Va., on Tuesday. (AP)

The 80-acre park is not fenced in, so officials are concerned Wood could have wandered off the property.

Hanover County Sheriff David Hines said 889 volunteers were trained and dispatched into a 2,000 acre search area. They joined some 300 professionals.

Wood does not speak, has blond hair and blue eyes. He was last seen wearing a red, long-sleeved T-shirt, blue athletic pants and blue shoes.