New Delhi: After hours of massive blackout, power supply was restored fully or partially on Sunday in several cities in Pakistan, including the national capital Islamabad. The power outage was reported shortly before midnight almost simultaneously in many cities as residents of Karachi, Rawalpindi, Lahore, Islamabad, Multan and others faced the blackout, said reports. Also Read - Secret Tunnel Used to Infiltrate Terrorists From Pakistan Detected in J&K's Kathua | Watch

Pakistan Energy Minister Omar Ayub Khan said that technical teams were working to fully restore the power supply. As per reports, the major outage was caused by a fault in southern Pakistan at 11:41 pm local time on Saturday (1841 GMT), Khan tweeted. “The fault tripped the transmission system of the country… leading to the shutdown of power plants,” Khan said. Also Read - China Pakistan Economic Corridor- Part 4- Chinese Mathematics of Debt

Islamabad Deputy Commissioner Hamza Shafqaat tweeted that the National Transmission Despatch Company’s lines have tripped, causing outage. “It will take sometime before everything gets back to normal,” he added. Also Read - China Pakistan Economic Corridor: When China Invested in Pakistan, They Did The Math

Power Minister Omar Ayub Khan said the frequency in the power distribution system suddenly dropped from 50 to zero, causing the blackout. “We are trying to ascertain what caused the drop in frequency, Ayub said.

Initial reports suggest there was a fault in the Guddu power plant in Sindh province at 11.41 pm, the Energy Ministry tweeted.

The fault tripped the high transmission lines and this resulted in the system frequency to drop from 50 to zero in less than a second, causing power plants to shut down, according to the ministry.

It added that Khan was overseeing the restoration work at the National Power Control Center. The minister appealed to people to maintain restraint and said power restoration was being carried out with caution and teams were on the ground.

Later, Khan also posted a series of tweets regarding restoration of power in several grids.