(BBC) – Electricity is gradually being restored in some areas of Pakistan following a huge power cut across the country, with every city reporting outages.
Homes nationwide were suddenly plunged into darkness from about midnight.
Officials appealed for calm but warned that it could take several hours before electricity is fully restored.
Power cuts are not uncommon in Pakistan. Essential facilities such as hospitals often use diesel-fuelled generators as a back-up power supply.
“A countrywide blackout has been caused by a sudden plunge in the frequency in the power transmission system,” Pakistan’s Power Minister, Omar Ayub Khan, wrote on Twitter in the early hours of Sunday.
Major cities, including Islamabad, Lahore and Karachi, were among those affected.
Mr Khan later said that power had been restored in some regions, including the city of Peshawar.
He added that an investigation was under way to determine the cause of the blackout.
Blackouts sometimes occur in Pakistan because of chronic power shortages, with many areas having no electricity for several hours a day. The issue has previously led to street protests.
In 2013, Pakistan’s electricity network broke down completely after a power plant in south-western Balochistan province developed a technical fault.