Power is gradually returning to major cities across much of Pakistan after the country of 210 million people was plunged into darkness just before midnight on January 9 by a breakdown in the national power grid.
Officials blamed the sudden blackout, one of the worst in Pakistan's history, on a technical fault in a complex and frail national power system in which local blackouts are common and the risk of domino effects high.
It was unclear whether there were any disastrous disruptions at hospitals or other vital sites, which in many cases rely on back-up generators because of the unreliability of networks.
"A countrywide blackout has been caused by a sudden plunge in the frequency in the power transmission system," Power Minister Omar Ayub Khan said on Twitter after the outage began.
By early on January 10, his Twitter feed had become a running tally of "energized" areas where electricity had been restored.
Authorities were scrambling to restore power and understand the reason behind the blackout, which impacted the capital, Islamabad, as well as major cities such as Lahore, Karachi, and Multan.
Internet connectivity across Pakistan "collapsed" and connectivity fell to below two-thirds of ordinary levels, according to web-outage monitor Netblocks.
The Ministry of Energy asked people to remain patient and cooperate as power began to be restored in some parts of the country in the early hours of the morning.
Islamabad was one of the first areas to get electricity back. Many areas of Lahore and Karachi were still waiting for power as afternoon approached on January 10.
Zafar Yab, a spokesman for the Energy Ministry, said both the Tarbela and Warsak power plants in northwestern Khyber Pakhtunkhwa Province were back online and power was being restored there.
The exact cause of the blackout was not immediately clear.
The Ministry of Energy said the Guddu power plant in the southern Sindh Province had a breakdown at 11:41 p.m. local time that impacted the national transmission system. The fault caused high transmission lines to trip and led to a drop in frequency to zero that caused power plants to shut down.
In 2015, around 80 percent of the country lost power due to a fault in a major transmission line.
