Firefighters are battling a blaze at a supermarket, police said today.
The fire is believed to have started at about 2.30am at Lidl, at Worle Parkway, in Worle, Somerset.
The fire rapidly spread throughout the roof and gas cylinders used for temporary heating during refurbishment appear to have been a significant contributor to the blaze, police said.
A statement from Avon and Somerset Police said: "The fire continues and it is anticipated that it will require cordon support throughout the morning and quite possibly through and beyond the afternoon rush hour period."
Commuter traffic is expected to be disrupted in the area as heavy smoke and large number of emergency service vehicles block routes.
An Avon Fire and Rescue spokeswoman said about 20 residents living in nearby Thorne Lane were evacuated from their homes. Some had gone to stay with relatives, while others were taken to a Sainsbury's supermarket.
Eight fire engines and two aerial appliances were tackling the fire, she said.
A number of roads had been closed, and trains were currently not stopping at Worle station, she added.