Avon Fire and Rescue Service was called to Sea Salt, on Bransby Way in Weston-super-Mare, at 3.39am, supported by Avon and Somerset Police.
An eyewitness said the fire affected the chippy, bins and the flat above.
The extent of the damage is unknown, but it is believed there were no injuries.
The cause of the fire is thought to be accidental.
An Avon Fire and Rescue Service said: “At 3.39am on May 22, crews from Radstock and Weston fire stations responded to a fire on Bransby Way, Weston-super-Mare.
“Firefighters used two breathing apparatus and two high-pressure hose reels to extinguish the fire. Thermal imaging cameras were then used to check for hotspots.
“The cause of the fire is believed to be accidental.”
The Weston Mercury has attempted to contact Sea Salt for comment.
