A $38,000 fire that damaged an Ocean Beach home early Monday was ruled accidental by the Metro Arson Strike Team. San Diego firefighters arrived at 4956 Narragansett Ave. to find one of eight single-family cottages engulfed in flames. Radiated heat caused the siding of another home to smolder. It took 20 firefighters about 20 minutes to put out the blaze, McNeill said. One firefighter suffered an eye injury and was treated at the scene. The owner of the cottage said he was awakened by a smoke detector and, when he opened his bedroom door he was confronted by a wall of flames. He then grabbed his dog and fled the cottage.