Smoke filled the community as flames shot out of Scotia Trawler Equipment Ltd. Firefighters from several communities raced to the scene to help out.
A call reporting the fire came in around 7:20 p.m. When they reached the three-storey building on Montague Street, emergency responders found it completely engulfed in flames.
Lunenburg Fire Services, assisted by numerous other fire departments from the area, worked all night to put out the blaze. There are no reported injuries.
CBC reporter Colleen Jones was at the scene. She said she could see flames shooting out of the roof of the building and that there was initially some concern there may be chemicals or flammable gas in the building.
She said emergency responders cut through the building's roof to gain access to the flames.
Residents said the wooden building was at least 100 years old.
Jones reported many onlookers worried the fire could spread to the waterfront's other historic buildings, many of which are also of wood construction.
She added the fire was nowhere near the iconic Bluenose II schooner, currently undergoing sea trials out of Lunenburg.
Just after 10:30 p.m., Jones reported that it seemed as though the fire was under control and contained to just the one building, but visible flames were still seen coming out of the roof.