Hartlepool firefighters have been called to a blaze at the former ambulance station on Elwick Road.
Crews from Hartlepool Stranton fire station were called to the incident at 7.28pm and four appliances remain on scene.
A Cleveland Fire Brigade spokeswoman said the building is 'well alight.'
Crews are tackling the blaze using a hydraulic platform and three hose reel jets.
More details to follow.