Hundreds of supermarkets across France were targeted in a cyberattack overnight, causing refrigerators and freezers to reach temperatures of up to 50 degrees Celsius and resulting in the spoilage of fresh and frozen food worth millions of euros.

The Paris prosecutor’s office announced on Monday that a “large-scale” attack was “affecting connected refrigerators in several major food retailers across France”, leading to food losses and fires.

According to reports, hackers managed to access the software that controls the temperature of refrigeration systems in more than 100 Coopérative U supermarkets and 180 Intermarché stores and its Netto brand outlets.

Intermarché’s spokesperson said the supermarket chain was forced to abruptly disconnect another 100 stores from the internet to prevent them from falling victim to further cyberattacks. The attacks took control of the software that allowed supermarkets to remotely control the temperature of their refrigeration units.

Other major food retailers, including Carrefour, Monoprix and E.Leclerc, were also reported to have been affected by the attack, as the perpetrators deliberately increased the temperatures of their refrigerators and freezers.

Reports noted that the full extent of the cyberattack remained unclear. However, figures released by individual supermarket chains indicated that about 400 of France’s roughly 15,000 stores were affected.

“Reliable refrigeration is critical to our customers’ operations, and we remain committed to supporting our customers and helping them maintain secure and reliable systems they are used to,” Danfoss, whose older refrigeration units were affected due to the inability to update their software, said.