Neighbors identified the victims as 12-year-old Austin Wiseman and 9-year-old Blake Campbell, The Columbus Dispatch said.
The Jackson County sheriff's office received a 911 call from a cellphone just after 11 a.m. Wednesday, authorities said.
The callers, the victims' grandparents, said the two boys were dead in an upstairs bedroom.
The home and an apartment above the garage were roped off Wednesday.
Authorities are releasing little information and would not say whether an arrest had been made.
Public records list James and Deborah Harris, the boys' grandparents, as the owners of the apartment garage and the home.
Kelly Lenoir Harris, 32, the mother of the boys, lives in one of the two homes, but authorities wouldn't say where she was Wednesday.
Autopsies were expected to be completed Thursday, the Dispatch said.
Wisconsin business offering 'therapeutic cuddling' forced to close
Campus cop fatally shoots Texas student during traffic stop