An early morning fire burned a portion of the Waiakea Uka gym Wednesday.

The fire broke out at about 4:30 a.m. at the county gym on Ainaola Drive.

Hawaii County fighters arrived at about 4:36 a.m. and found flames coming from the northeast corner of the building.

About a third of the roof burned before firefighters were able to bring the fire under control at 4:45 a.m. and extinguish it by 4:55 a.m.

Firefighters estimated the damage at $65,000. They also estimated they were able to prevent $225,000 damage if they had not stopped the flames from destroying the rest of the 80-foot by 90-foot structure.

The cause of the fire is under investigation.