Winnipeg fire crews are busy Friday night battling a large fire in the city's downtown area.

The fire broke out around 7:43 p.m. in a three-storey building on Main Street near the Disraeli Freeway.

Heavy smoke and flames were pouring from the building when crews arrived at the scene. Firefighters attempted to fight the fire from inside the building, but they were quickly forced to retreat due to deteriorating conditions.

Crews are now fighting the fire from outside the building, using aerial ladder trucks and hose lines to apply water to the fire.

Crews are expected to remain on scene through the night working to ensure the fire is fully extinguished. 

As a result, Main Street is closed in both directions between Logan Avenue and Alexander Avenue while firefighters work to put out the blaze.

No injuries have been reported.

The building is expected to be a complete loss.

The cause of the fire remains under investigation.