Firefighters were called to Hanover Road around 3.30pm to reports of a blaze.
An eye-witness said the windows were smashed and that smoke was coming out.
The road is currently closed at both ends for both cars and pedestrians.
Traffic is building up on Victoria Road and the surrounding areas.
Breathing apparatus and hose-reels are in use by the fire service and an aerial platform is also in attendance.
The blaze is said to be under control.