TOWN OF NEWARK, Wis. -

A body was found inside the house where crews were fighting a fire in Rock County Tuesday morning, officials said.

Firefighters responded at 6 a.m. to a report of a fire in the town of Newark, about 15 minutes west of Beloit, on West Highway 81. The fire was knocked down by 9:40 a.m.

Officials said a neighbor reported the fire at 10316 Highway 81.

The Rock County Sheriff's Office confirmed a body was found inside the basement after the house collapsed.

Officials said identification of the person is being withheld pending positive identification and notification of family members.

Highway 81 was closed between Olson and Merlet roads Tuesday morning as crews investigated. The road was reopened around 4 p.m.

A special agent with the Division of Criminal Investigation was seen surveying the house. State fire marshals are also at the house investigating the cause and origin of the blaze.

"It’s suspicious. We need to determine, if we can, what caused this fire, where it started, how the person died? Was it fire-related or possibly something else," Rock County Sheriff's Office Capt. Todd Christiansen said. "The floor is all collapsed. The roof is collapsed, so everything is in the basement."

Sheriff's officials said the homeowner's truck is also missing from the property.

The truck is a 1997 red Chevrolet S10 extended cab pickup truck with Wisconsin license plate KY5-599.

"We're just looking to see who has that and where they're at," Christiansen said. "If they were here within the last 24 hours or not, or why the truck is not here."

Crews on scene told News 3 a shed on the property had previously caught fire, but a cause was never determined.