Hundreds of French supermarkets saw their refrigeration systems defrosted, spoiling tons of frozen food. The unprecedented attack has raised serious questions about food security across Europe.

Hundreds of French supermarkets were forced to throw away perishable goods on Monday after hackers commandeered refrigeration systems across the country, spoiling stock at major chains in a sophisticated overnight cyberattack.

Hackers destroyed the food by taking control of refrigeration systems at Cooperative U, Leclerc, Les Mousquetaires, and Intermarche stores across the country and then defrosting thousands of freezer and refrigeration units.

During the overnight attack, in some cases, fully-stocked fridges were heated up to 50 degrees Celsius (122 degrees Fahrenheit) for more than six hours. Over 400 stores were hit according to retailers.