Three-quarters of fast food outlets in the Bridgwater area inspected by officers have failed fire safety checks.
Some have been issued with notices restricting the use of premises after checks were carried out by trained fire protection officers from Devon and Somerset Fire and Rescue Service.
Inspectors visited 30 fast food venues in the past three months, and 20 did not comply with current legislation.
Four premises were so dangerous that restrictions of use notices have been served, the fire service said.
Fire safety check inspector John Unwin said: “We were shocked to find that 75 per cent of the fast food outlets we visited required some form of enforcement action.
“It is the responsibility of business owners to ensure they comply with fire safety legislation. We would rather help them to make their premises safer for their customers with advice but if we have to take firmer action, we will do so.”
The fire service will hold a free event for fast food outlet owners and managers in Bridgwater at Blake Hall tomorrow, from 3pm to 6pm.
Fire protection officers will explain the legal obligations given to people responsible for businesses under the Regulatory Reform (Fire Safety) Order 2005. There will also be the opportunity to speak with officers on specific issues.
Crew manager Unwin said: “Fire safety is especially important where people may be asleep in rooms or flats above a business and their access is by a single, open or unprotected staircase from the main public or kitchen area.”