A trailer fire that damaged an office for Iron Horse Towing early Sunday morning in Kalaeloa is believed to be arson.

Crews arrived on scene at 91-1085 Enterprise Avenue at about 5 a.m. Firefighters made forcible entry into the trailer and had the fire under control and extinguished within 10 minutes, a spokesman for the Honolulu Fire Department said.

A fire investigator classified the blaze as intentional and the case was transferred to a Honolulu Police Department arson detective, the spokesman said.

Damage is estimated at $25,000.