Power to the capital of Islamabad was restored hours after a major outage plunged Pakistan into darkness Saturday, according to officials.
The breakdown, one of the worst in recent years, was caused by a "technical fault" in the national power distribution system, which subsequently broke down a main supply line, said the Ministry of Water and Power.
The electrical failure hit Islamabad and the commercial capital of Karachi, as well as Lahore, Rawalpindi, Multan, Faisalabad, Hyderabad, and parts of Pakistani-administered Kashmir.
A spokesman for the Water and Power Ministry said the supply frequency "suddenly" plummeted to zero, causing a major breakdown across the country.
He said the ministry constituted a six-member committee to investigate the blackout and fix the problem.
Initial reports said a major power plant developed a fault at 11.41 p.m. (1841GMT) Saturday, dropping the frequency to zero and causing high transmission lines to trip.
The reason for the sudden drop is unclear.
The breakdown also sent important government buildings and institutions, including the President House, Prime Minister House, parliament, Supreme Court airports and others to backup generators.
Urging residents to remain "patient," Water and Power Minister Omer Ayub Khan said efforts are underway to restore electricity to remaining areas as soon as possible.
"I am personally overseeing the restoration process," he said in a tweet.
Power outages are not a rare occurrence in Pakistan.
In January 2019, a major outbreak caused by tripping a circuit of the national grid, because of dense fog, plunged southwestern and southern provinces into darkness for hours.
By Aamir Latif in Pakistan