Neighbor Mary Gentry said she heard the sirens at about 2:30 a.m.
"I saw the flames shoot up, and I said, 'Oh my God, the house next door is on fire,'" Gentry said.
About 40 firefighters from Wayne Township, Speedway, Decatur and Indianapolis fire departments battled the blaze for an hour before gaining control of the flames that engulfed the 4000 sq. ft. home.
"The whole building was consumed by fire when our firefighters arrived on scene," Pruitt said. "When they go on a fire that's been set, many times there are things in these fires our firefighters face that they wouldn't see in a normal fire: from booby traps to whatever's been used to start the fire can cause it to burn more intensely."
Pruitt said arsons present great dangers to firefighters and nearby houses are also at risk.
The U.S. Fire Administration reported an estimated 16,800 fires are intentionally set in residential buildings each year and 41-percent of those occur in vacant buildings, for nearly $600 million in property losses.
"To some it's just to cover up another crime, for profit or revenge. And the amount of property damage, potential injury and loss of life is significant," Pruitt said.
Wayne Township firefighters are offering a reward of up to $5,000 for information about the fires leading to an arrest.
Anyone with information is asked to call Wayne Township Fire Department at 317-247-8501.