The firefighters intervened at the Carrefour Market supermarket in Monistrol-sur-Loire this Saturday morning.
They were called after the fire alarm in the technical room of the establishment was triggered by the strong release of smoke from a capacitor, around 9 a.m.
The supermarket manager used a fire extinguisher on the capacitor, which had not caught fire.
He was assisted by a firefighter present as a customer in the supermarket. The firefighters arrived then, called by the director as a precaution.
The time to settle the incident, ie for a good half hour, the customers were evacuated from the shelves. An electrician must come this Saturday afternoon to determine the origins of these fumes.