Firefighters turned out in force in downtown St. John's early Tuesday morning after flames burst out of a law office on Duckworth Street, just west of the courthouse.
No injuries were reported in the fire at the Noonan Law building, which drew crews around 4 a.m.
Supt. Don Byrne said there was dense smoke coming from the building when the first trucks arrived at the two-storey building.
"It was issuing from all floors, all windows," Byrne told CBC News, adding that crews had a bit of trouble getting in the building.
"All the windows on the Duckworth Street side were all barred up with plywood," said Byrne.
Lawyer Ed Noonan, one of two lawyers working in the offices, said the fire appears to have started in the furnace room.
Most of the damage appears to be in the basement of the building, although Byrne said that the fire appeared to spread to upper levels through an interior wall.
A large fire department presence was on hand in the early minutes of the fire. A ladder truck was later sent back to its station once firefighters were sure there was no chance that the fire would spread to nearby buildings.
"Whenever you tip into downtown St. John's, we always bring extra resources," he said.
A section of Duckworth Street was temporarily closed to traffic as crews cleaned up.