Kane County sheriff's deputies said the boy was discovered unharmed but disoriented at Anderson Elementary School in St. Charles about 1:30 a.m. Sunday, the Aurora (Ill.) Beacon-News reported Wednesday.
Sheriff's Lt. Pat Gengler said the boy was having trouble remembering his address and told officers he was at the school to watch a movie with his mother. Gengler said the boy's mother had discussed a movie night with him Saturday.
The boy was taken to Delnor Hospital in Geneva, Ill., where a school district official identified him and determined his address. Gengler said the child's parents were sleeping when deputies brought him home.
"This is just kind of one of those way-out-there things," Gengler said. "We're lucky and we're happy it turned out this way. If it was December or January, it could have been a sad ending."