Emergency services responded to the Carrefour supermarket in Audun-le-Tiche on Tuesday morning after carbon monoxide was detected inside the store.
At around 7am, five employees began to feel unwell, experiencing symptoms such as dizziness and nausea.
According to initial findings, the source of the carbon monoxide leak was a cleaning machine that had been stored in an inadequately ventilated space. A battery fault in the machine reportedly led to the release of the gas.
The supermarket remained closed until 10.30am while firefighters secured the premises and carried out the necessary safety checks. Four of the affected employees were able to return to work later that morning, while one was transported to hospital due to respiratory problems.
Firefighters remained on site for approximately two hours to ensure the area was safe and to conduct further inspections.
