A director at Kettering Bedding Centre fled the burning building moments after a fire took hold in its roof.
Fire crews are still tackling the blaze at the Regent Street shop, which started at lunchtime today (Monday).
The shop is part of F.L.Caswell, in nearby Montagu Street, and directors Anthony Caswell-Jones and Robert Jones stood watching emergency services do their best to save the building from behind a cordon at Rockingham Road at about 2.30pm.
Anthony was the only worker in the shop at the time and described the moment he fled the building.
He said: “Someone was working on the roof doing repairs and then I heard the smoke detectors going off.
“There was quite a big fire on the roof.
“I grabbed a fire hydrant and then the smoke just hit me so quickly.
“I got out and rang 999.”
The unit extends all the way back from the frontage on Regent Street to Havelock Street. The fire is believed to have started in the middle but its cause is not yet known.
Smoke billowed from the roof and was visible across the town.
Beds and mattresses inside the building soon caught fire with windows across all three floors smashed as flames engulfed the front of the building.
One resident said a van nearby also caught fire.
F.L.Caswell is a family-run business which started in 1926 with Kettering Bedding Centre opening in the late 1960s.
Anthony said he was “devastated” and Robert said he was “upset” by the blaze.
Anthony added: “Not only that but we’re going to let our customers down.”
He added that he didn’t believe there was any asbestos in the property.
Details of whether the fire has spread have not yet been confirmed.
Fire crews are still battling the blaze and dousing the flames with pumps with one on an aerial platform tackling the fire on the upper floor.
Emergency services are wearing face masks to protect themselves from the ash in the air.
Robert Moth, who lives in Canon Street, was among those watching emergency services tackle the blaze.
He said: “I heard lots of sirens and looked outside and saw a lot of smoke belching in the area.”
Residents are asked to keep their doors and windows shut to keep the smoke out while the fire service deals with the incident.
Motorists are also advised to avoid the area.
Several roads in the area are closed.