Firefighters in New Westminster battled a large fire at Frankie G's pub in Queensborough early Friday morning.

Crews arrived just after 1 a.m. to the pub on Ewen Avenue, to find thick smoke coming from the roof of the building.

A tower unit sprays water over the roof of the pub. (Gian-Paolo Mendoza/CBC)

Around 20 firefighters spent over three hours battling flames and hotspots inside the pub, which was closed at the time.

Battalion Chief Tim Armstrong said Friday the fire was difficult to fight, but a strategic attack prevented it from becoming much worse.

Battalion Chief Tim Armstrong says crews managed to keep the fire under control with a a strategic and aggressive attack. (Gian-Paolo Mendoza/CBC)

"This was a stubborn fire, in that the roof structure is all vaulted on the inside, and it's polyurethane foam insulation in the roof," said Armstrong.

"That foam insulation started to burn and penetrate up to the roof."

Armstrong says despite the the amount of time it took crews to contain the fire, the pub only sustained damage to the roof of the building.

Despite the intensity of the fire inside, the pub only sustained minor damage to the roof of the building, according to the fire department. (Gian-Paolo Mendoza/CBC)

"There's going to be some water damage on the floors ... but crews did a really good job aggressively attacking the fire, knocking it down quickly."

The cause of the fire is currently under investigation, although Armstrong says it is not considered suspicious at this time.