Power supply was restored in many parts of Pakistan by Sunday afternoon after a massive power breakdown led to blackouts in several parts of the country from Saturday night, reported the Dawn.

Energy Minister Omar Ayub Khan said that the services were restored fully or partially in many cities like Islamabad, Rawalpindi, Lahore, Multan, Karachi and Faisalabad but it would take some time before the situation returned to normal across the country, according to PTI. In a series of tweets, Khan listed the areas where power supply had been reinstated.

Meanwhile, Khan told reporters that the power supply snapped at 11.41 pm on Saturday after a technical fault at Guddu power plant in Sindh province, which led to a sudden drop in system frequency. Terming the phenomenon a “cascade effect”, the energy minister said that safety systems of one after the other power plants shut down. He said that investigations were underway to find out the cause of drop in frequency.

Information Minister Shibli Faraz said that the transmission system was old and blamed previous governments for neglecting it.

Earlier during the day, as blackouts were reported on social media by residents of major cities like Islamabad, Lahore, Karachi and Multan, Pakistan’s ministry of energy tweeted about the fault. “The fault caused the country’s high transmission lines to trip, which in turn caused the system frequency to drop from 50 to 0 in less than a second,” the ministry had said. “The drop in frequency caused power plants to shut down.”