The RCMP say the major fire that severely damaged a decades-old building on Lunenburg, Nova Scotia's historic waterfront may have been caused by electrical problems.

An electrical engineer examined the scene of the fire at the three-storey Scotia Trawler building and said that the cause appeared to be "electrical in nature," RCMP Cpl. Ted Mugford told The Canadian Press Saturday afternoon.

The fire isn't considered suspicious and the fire marshal will take over the investigation, he added.

Earlier Saturday, firefighters were called back to the site of the fire – which is believed to be nearly a century old-- to extinguish a small spot fire.

Fire Chief Darren Romkey said it's likely that the building has to be demolished.

"The engineers will probably come in to determine that," Romkey told CTV News. "There's pretty extensive damage to the roof and the interior is scorched pretty bad.”

On Friday evening, it took firefighters almost four hours to get the blaze under control.

Romkey said firefighters received the call Friday evening after somebody noticed the flames from across the Lunenburg harbour.

By the time fire crews arrived at approximately 7:30 p.m., the building was engulfed in flames. They struggled to fight the blaze due to the building's old age and construction, Romkey said.

About 150 firefighters from 15 different stations helped battle the blaze, he said. No one was injured.

There were concerns the fire might spread to nearby buildings on the waterfront – which is a UNESCO World Heritage Site -- but firefighters doused nearby structures with water to keep them from igniting.

If the building has to be torn down it will be missed, Romkey said.

"If you look at any picture that a tourist may buy from town of the waterfront, it is a large red structure right in the middle of all the buildings on the waterfront, so if it is actually torn down, it's going to leave quite a hole there."

Donald Wilson witnessed the fire Friday night. He said he's also worried about a "hole" along the waterfront.

"It’s a blemish on our streetscape," he said.

RCMP said there were two vehicles and some tools inside the building – which acted as a marina storage space.

A boat and a car were damaged in the fire, officials said.

With files from CTV Atlantic and The Canadian Press