Fire damaged a room in a two-story boarding house in Kalihi this morning.

Firefighters responded to the 8:59 a.m. blaze on the first floor of the wooden structure on Kamehameha IV Road, just makai of School Street, and extinguished it by 9:20, said Capt. Robert Main, Honolulu Fire Department spokesman.

Estimated damage was $18,000 to the structure and $2,000 to its contents, Main said. The cause and origin of the fire were still under investigation but it was believed to have started in the cooking area of a one-room unit on the first floor, he said.

A man living in the unit was not home. Three other people living on the second floor escaped without injury. Main credited a smoke detector on the first floor for alerting those home about the fire.