JACKSON: Preliminary autopsy results indicate a 12-year-old boy shot his 9-year-old half brother and then shot himself at their grandparentsí home in southern Ohio, the county coroner said Thursday.

Each boy had a gunshot wound to the head, Jackson County coroner Dr. Gregory P Hawker, told media outlets. Itís unclear whether the first shooting was an accident.

Jackson City Police identified the boys as Austin Wiseman and his younger sibling, Blake Campbell. Police said they lived at their grandparentsí home, where the shootings occurred Wednesday in an upstairs bedroom. Investigators donít believe anyone else was involved in their deaths.

Authorities have said that the grandparents were away at the time of the deaths, and that a .44-caliber handgun was recovered.

The Ohio Bureau of Criminal Investigation was examining evidence collected from the home as authorities tried to determine what happened.

A man at the home who identified himself as an uncle said he had no comment Thursday afternoon.

The two-story house is set back slightly from the road in an older neighborhood with a mixture of residential houses and businesses.

Hawker told the Associated Press on Thursday that he couldnít comment on what might have led to the shootings, but authorities say no one else was at home at the time.

Hawker said the boysí maternal grandparents had left the home to take care of some personal business but had talked to the boys by phone at about 10 a.m.

Itís believed the shootings happened at about 11 a.m.

Jackson is a city of about 7,000 people in mostly rural Appalachian Ohio.