Firefighters were called to the scene of a fire at the city depot in St. John's late Friday morning.
Crews from the St. John's Regional Fire Department responded to the call shortly before 11:30 a.m.
Supt. Derek Chafe said a city street sweeper caught fire while inside the Blackmarsh Road facility.
According to Chafe, the vehicle was being worked on at the time the fire started, but crews are unclear how the fire broke out.
He said mechanics working on the sweeper tried unsuccessfully to extinguish the flames.
"There was a fire started up in the back end of the vehicle, and although there wasn't a lot of a flame there was a lot of dark heavy smoke that completely filled the building making visibility just about nil," said Chafe.
Chafe said it took some time to clear the heavy smoke from the building.
No one was injured in the incident, and damage was contained to the single street sweeper.