Specialist technical rescue officers were seen cutting into the side of the building to gain access as fire chiefs urged people to avoid the area if possible.
A spokesman for West Midlands Fire Service said: "We are currently dealing with a large incident at Fox's Lane, Heathtown in Wolverhampton.
"We have 10 appliances plus specialist equipment in use. Please avoid this area if possible if you are local to this incident."
An incident response vehicle from West Midlands Ambulance Service was also present, but it is believed nobody was injured in the blaze and everyone has been accounted for according to the fire service.
Firefighters were continuing to battle the blaze into the afternoon.