A building at a boat yard on Norwalk Harbor was damaged by flames Tuesday evening. Firefighters were called around 6 p.m. to 108 Water St., the Landan and Rondano Marine repair shop. Deputy Fire Chief Chris King said arriving firefighters found heavy smoke coming from the roof, office door and an office window. They forced open the door. The crew from Engine Five entered the office and encountered heavy flames, King said. King said the flames did not spread outside the office because all the doors were closed that led to the rest of the repair shop. The emergency response was sizable because firefighters worried about the possibility of explosions at the boat yard — 25 firefighters plus police and medical personnel.