Crews and appliances from Fareham, Gosport, Portchester, Cosham and Southsea are likely to remain at the scene for some time as they battle to gain control of the blaze that is released thick toxic smoke into the air as the building is understood to contain a large number of lithium batteries that are at risk of exploding.
The cause of the blaze is not currently known but under investigation
Large flames can be seen leaping from the building and smoke billowed high into the night sky as teams doused the building with water and foam.
Officers in command at the Incident have advised residents to keep windows and doors closed whilst they tackled the developing blaze.
More to follow