Hawaii County fire investigators suspect a fire that caused $20,000 damage to a Keaau home under construction was deliberately set.

The fire broke out at 4:27 a.m. Thursday at a home being built on a lot between Paradise and Kaloli drives.

Firefighters brought the fire in a hallway and living room of the 1,000 square foot structure under control by 4:38 a.m. and extinguished it by 4:40 a.m.

Fire investigators believe an incendiary device was used to start the fire.

Police were also on scene.