A massive fire ripped through downtown New Westminster early Thursday, destroying at least 40 businesses and erasing a century of history.

Police and fire crews were first called to a structure fire at 634 Columbia St. at around 4 a.m.  A Vietnamese restaurant called Le Saigonnais is listed at that address.

The fire quickly spread, threatening dozens of businesses, including bridal stores, coffee shops and offices – many housed in a 100-year-old heritage building.

Crews were faced with a dangerous battle as the blaze tore its way through two buildings, leaving power lines sparking in its wake.

Witnesses said loud explosions could be heard from across downtown New Westminster.

“It went from like, just a little sliver to this. I came here and I was just one block away and I could feel the heat from the flames,” Tim Eliason told CTV News.

About 40 businesses operated out of the two buildings, with a dozen completely destroyed in the fire and many others affected – along with their owners.

Lynn Quesnel was helpless as she watched her store Moody Beads burn.

“I’m kind of feeling a little stressed, but you know what? It happens and we can’t do much,” she said. “It’s not like I can go and rescue my bead store right now.”

New Westminster’s Fire Chief said propane tanks on the roof of the building, which were being used by a roofing crew, caused the explosions during the fire.

But the cause of the blaze, which broke out at around 4 a.m., remains unknown.

“These buildings, you have to remember, are tinder dry. Some of them are over 100 years old, so they’re all wood-frame buildings,” Tim Strong said.

New Westminster Mayor Wayne Wright said it was a sad day for the former provincial capital.

“This is the historical area of our downtown and what we’re trying to salvage and what we’re trying to reproduce,” he said. “This is very unfortunate because one of the main buildings was Copp’s Shoes.”

The 85-year-old business was one of the first to go, collapsing in just 45 minutes, taking decades of history with it.

“Waves of emotion go through your mind,” said Terry Brine, a co-owner since 1971. “You’re thinking of what’s happened in the past and generations before, never to be the same again.”

The fire caused the closures of several main roads, including Front, Columbia and 6th Streets.

Police asked drivers and pedestrians to plan alternate routes while crews got it under control.

Firefighters are still on scene and an investigation into the cause of the fire is ongoing.

With files from CTV British Columbia's Norma Reid and Nafeesa Karim