LYNN – Fire ripped through a small single-family home at 51 Green St. shortly before noon Thursday. Neighbors alerted the six occupants who fled the flames unharmed.Fire Lt. David Legere, head of the city’s arson squad, said the fire was caused by combustibles left too close to an electrical space heater.Dozens of firefighters battled the fire that belched black smoke across the residential neighborhood and the adjacent commuter railroad tracks. The firefighting was complicated by the house location at the end of a hilly, narrow driveway off Green Street. Although the fire was quickly extinguished, fire crews remained at the scene into the early afternoon to overhaul the structure and douse hot spots.Two Lynn men who live in the area said they spotted the flames and warned the occupants to get out of the house. The men said they broke a few windows to release the smoke, not realizing that doing so would fan the flames until a police officer explained the situation.”There were six people in the house, five adults and one child. They claimed they were all sleeping in the bedroom on the second floor when they heard the smoke detector go off,” Legere said.Although the two neighborhood men were praised for their rescue efforts, Legere said smashing windows in a burning house could have led to tragedy. “The last time somebody did that in Lynn, five people died,” he said. “It’s great that you try to wake people in the building, but breaking windows can really hamper the fire fighting.”City records indicate the five-room home, built in 1900, is owned by Juan Batres who purchased the property in 2003.An addition to the gabled, vinyl-sided wood building with asphalt roof was destroyed. Fire and smoke damage appeared extensive.The Red Cross has since provided the victims with shelter.