In Pakistan, the nationwide power supply collapsed in the early morning hours on Monday.
According to the Pakistan Energy Ministry, it could take up to 12 hours for the power outage to be resolved in all parts of the country.
Most of the country's more than 220 million inhabitants were affected by the outage, including in the megacities of Karachi and Lahore.
The reason for the collapse was a frequency drop in the nationwide power grid, as announced by the Ministry of Energy on Twitter.
After the start of the repair work, the power supply was restored first in parts of the capital Islamabad and the north-western city of Peshawar.
The port city of Karachi, with its more than 15 million inhabitants, and the second largest city, Lahore, with more than ten million inhabitants, were initially left without electricity.
Currently, power generation is off at night due to lower consumption during the cool months.
According to the Ministry of Energy, when generation was restarted in the morning hours, fluctuations occurred that ultimately paralyzed the power grid.
Authorities called on the population not to panic.
Power outages are more common in Pakistan - but not that all major cities are cut off from the supply at the same time.
The risk of power outages has increased due to the economic crisis and this summer's catastrophic floods in the South Asian country.
It was the second widespread power outage in Pakistan in two years.
Pakistan's power grid is prone to problems in one part of the country affecting supplies across the country.
In January 2021, a fault in the power grid in the south of the country had plunged the entire country into darkness.