Dozens of firefighters have been tackling a fire at a store in Blackwood High Street.
The service says it started at around 2 o'clock this morning
There are no reports of injuries.
Firefighters were drafted in from Cefn Forest, Abercarn, Cardiff, Cwmbran and Merthyr.
Local residents are being asked to keep windows and doors shut.
The street's closed but other roads in the area are also likely to be affected.