Electricity is gradually being restored in Pakistan following a huge power cut across the country, which led to every city reporting outages.
Homes nationwide were suddenly plunged into darkness from about midnight.
Power is now back in most cities but officials warn that it could still be a few hours before electricity is fully restored.
The outage is believed to have been caused by a fault at a power plant in the south of the country.
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.
Mr Khan later said that power had been restored in most major cities but that it would take a few more hours for the grid to go completely back to normal.
He added that the outage occurred after a fault developed at the Guddu power plant in Sindh province shortly before midnight on Saturday (19:00 GMT).
Investigators were at the site to ascertain the cause of the fault, Mr Khan said.
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.