Firefighters on scene are from Redbridge, St Mary’s, Hightown, Fareham, Eastleigh, Beaulieu, Lyndhurst, Hamble, Fleet and Ringwood.
The aerial ladder platform from St Mary’s and Romsey’s environmental protection unit are also in attendance.
The workshop, used for vehicle repairs and bodywork, is on Old Redbridge Road.
The building – measuring 35x by 40m – is 100% involved and divided into three sectors for firefighting.
A 200m cordon has been put in place whilst emergency crews work.
HIWFRS will be on scene for a significant time and we ask that the public avoid the area due to road closures in place.
We advise that local residents keep their doors and windows closed as there’s a lot of smoke coming from the scene.
Approximately ten people have been evacuated from local properties.
A relief strategy is currently being put into place.
Incident Commander Ben Allen said, “Thanks to the tactical positive action from the firefighters who arrived first on scene, the extent of the fire has been limited to the property, and the surrounding buildings are unaffected.
“We’re pleased to share that the incident is now scaling down, and all cordons and road closures have been lifted.
“Many thanks to our partners and all the HIWFRS crews for working together to bring this incident to a close.”
Investigations into the cause of the fire are ongoing but are not believed to be suspicious.
The stop message came in at 12:08, with the fire being extinguished using two breathing apparatus, six jets and an aerial ladder platform.
One crew of firefighters will remain at the scene to continue to damp down and turn over.
The building has been 100% destroyed by the blaze.