Firefighters are tackling a blaze at Prezzo restaurant in central Harrogate.
The roof of the restaurant has collapsed, and 70 firefighters from across Yorkshire are now battling the blaze.
The fire broke out in the kitchens of the Albert Street restaurant and has spread to flats above.
Firefighters are smashing windows in order to prevent glass spraying in case of an explosion.
Lee Smith is Area Commander for Harrogate Fire Service.
He said: “We’ve been trying to establish the exact location within the building. We did withdraw our firefighters who had been inside because of the conditions - it’s not safe inside.
“We are still trying to establish that everyone got out ok, although we have no cause for concern.
“We can see from the colour of the smoke - a brownie colour - that we could be facing a potential explosion.
“12 engines from across the county including incident command units and aeriel ladder platforms are in use.
“The fire is contained in Prezzo and the flat above.”
Emergency services have cordoned off much of the town centre because of the fumes. They were first called to the scene at 11.30am.
Firefighters had initially been inside Prezzo, but were removed from the building because staircases and walls within the building collapsed.
Area Commander Smith said: “We have taken precautionary measures to minimise the damage.
“I imagine a lot of stairs will have been burnt away and the walls have come down. We are talking to people and urging them to move away.
“We have moved outside and are getting access through the windows. It’s a very complicated and difficult fire. There are lots of spaces between windows and floors which is allowing the fire to move around the building.
“it’s part of the design of these old building in Harrogate, it’s full of nooks and crannies allowing the fire to spread.
“We are chasing it. We believe it started in the extraction area.”
The fire service confirmed a full investigation will take place, and they are expected to be at the scene until Thursday.
Paramedics are at the scene in case firefighters are injured.
The service urged people to stay away from the area, and to close windows and doors.