The cause of Monday’s Pacific Heights Road house fire was a generator exhaust that was too close to stored combustibles in the garage, the Honolulu Fire Department said today.

Fire investigators determined the blaze was accidental.

Damage to the home was $260,000 to the structure and $80,000 to its contents.

The three-story home’s garage was fully involved in flames when firefighters first arrived at 2:02 p.m. The fire, reported at 1:56 p.m., was brought under control at 4:15 p.m. and extinguished at 6:23 p.m.

Two adult brothers, who lived in the home at 2455-C Pacific Heights Road, managed to escape unharmed.

One brother was working in the lower floor when he heard popping noises. He woke his brother, who was sleeping, and the two escaped.

One neighbor said there had been a lot of items stored in the garage, as well as a truck.

The entire garage and the right front corner of the house collapsed.

Firefighters took nearly four and a half hours to extinguish the fire.

Part of the difficulty was initial low pressure from the water supply. Also the collapsed portions of the house and garage made it difficult to completely extinguish. A downed powerline also posed a hazard to firefighters.

The home did have working smoke alarms, but no fire sprinklers.