The fire that badly damaged a 100-year-old building on the historic waterfront in Lunenburg, N.S., started accidentally, the fire marshal says.

The blaze ignited around 7 p.m. on Friday and crews from 15 stations battled it for 11 hours. The fire was extinguished by 6:30 a.m. The building's roof was destroyed and the inside was badly damaged, but its four walls and two floors remain standing. 

"The Office of the Fire Marshal is looking into the electrical [system]," said spokeswoman Chrissy Matheson. 

Fears for UNESCO site

Lunenburg Fire Chief Darren Romkey said he thought the building could be salvaged. No people were inside, he added. 

As the blaze roared on Friday night, locals feared it would spread along the many wooden buildings on the waterfront. The crews were able to contain the fire to one building.  

The fire marshal was expected to visit the site on Saturday to investigate the cause. 

The building is owned by Waterfront Development, a provincial crown corporation that oversees waterfronts in Bedford, Dartmouth, Halifax and Lunenburg. 

The building has a business tenant with an office and storage.

Lunenburg was established in 1753 and the downtown is a UNESCO World Heritage Site.