A record-breaking heat wave sweeping across Europe has triggered a major power outage in France, as several countries place large areas under red-alert warnings.

In western France, a heat-related failure left about 68,000 households without electricity, according to authorities in the coastal department of Finistère.

The blackout began on Tuesday evening after a transformer malfunction in the town of Ergué-Gabéric. Officials said power restoration was not expected to be completed before the end of Wednesday at the earliest.

“Priority is being given to restoring power to healthcare facilities and critical sites. Nursing homes where power has not yet been restored to the grid will be provided with generators,” the operator said in a statement.

Data from French utility EDF showed that the country’s nuclear power output fell by 4.1 gigawatts on Wednesday as soaring temperatures limited access to cooling water for reactors, according to Reuters.

The development comes as a new wave of record-breaking heat sweeps across Europe, disrupting school operations and transportation services in several countries across the region.

France recorded its hottest day ever on a nationwide basis on Tuesday, according to the country’s weather agency, Météo-France.

The agency reported a temperature of 44.3 degrees Celsius (111.7 degrees Fahrenheit) in the southwestern town of Pissos, while several cities experienced what it described as unprecedented temperatures for the time of year. Among them was Bordeaux, where temperatures climbed to 42.1 degrees Celsius.