Fire levelled a commercial building in the Goulds area of St. John's overnight.
No one was injured in the fire, which broke out on Roberts Road.
St. John's Regional Fire Department crews could see the flames from at least a kilometre away when they arrived shortly after 2:30 a.m.
Supt. Don Byrne said there was no way to save the building, which housed a welding business and a couple of storage areas.
"Right now they're on the inside and there's some deep-seated fire in one of the storage areas," Byrne told CBC News Wednesday morning.
"It's just hard to get at, so they are just tearing about the deep-seated area there, and making sure all the hotspots are extinguished."
The Royal Newfoundland Constabulary said its investigators would be on scene Wednesday to determine whether arson might have been involved.