A major power outage has hit the Western Balkans as the region swelters in an early heat wave that has sent temperatures soaring to up to 40 degrees Celsius, or 104 degrees Fahrenheit.

A major hourslong power outage hit much of the Balkans on Friday as the southern European region sweltered in an early heat wave that sent temperatures soaring to more than 40 degrees Celsius (104 degrees Fahrenheit).

Montenegrin authorities said that an outage that lasted for several hours in the country’s power distribution system left almost the entire nation without electricity, while similar problems were reported in the coastal part of Croatia, and in Bosnia and Albania.

Nada Pavicevic, a spokeswoman for Montenegro’s state power distribution company, described the outage as a “disturbance of regional proportion,” and said authorities were still working to determine what happened.