It happened a little after 6:15 Sunday evening in the 1100 block of E. Forrest Hill. Firefighters arrived to find a fence on fire.
Flames eventually spread to the back of the house.
Everything was under control in a few minutes. Firefighters said the owner was not inside, but two small children were in the backyard at the time of the fire.
The owner said he was using a grill to cook food.
A fire investigator thought the kids might have used lighter fluid to start the fire.
The Red Cross is helping provide shelter for the two kids and two adults. Damage is estimated at $15,000.