Investigators are trying to determine the cause of a restaurant fire that killed a man over the weekend. Fire crews responded shortly after 2:30 a.m. Sunday to the blaze on Ruiz Street at a building that was the former home of a Mexican restaurant. Firefighters were told there may be someone inside, and later found a 65-year-old man in the building who was unresponsive. Life-saving measures were unsuccessful, and he was pronounced dead at the scene. Investigators believe he was the owner of the restaurant.