Pakistan’s national power grid suffered its second major failure in three months on Monday, stranding millions without electricity and, in some instances, drinking water, multiple outlets have reported.

The outage was caused by a “large voltage surge in the south of the grid, which affected the entire network,” Reuters reports, per Energy Minister Khurrum Dastagir. It is unclear at the moment how long the outage will last, though restoration efforts are already underway, CNN adds. Dastagir said the government is hoping things are back to normal by tonight, per The Associated Press.

A separate senior official blamed this blackout and others on the country’s aging infrastructure. “There’s an underlying weakness in the system,” the official told Reuters. “Generators are too far from the load centers and transmission lines are too long and insufficient.” And separately, some of the country’s roughly 220 million residents suffer from almost daily blackouts, Reuters adds.

The Monday outage comes as Pakistan otherwise struggles with a larger economic and energy crisis, due to which Prime Minister Shehbaz Sharif earlier this month ordered both federal departments and public citizens to cut back on energy usage and consumption.

The incident also calls to mind a similar widespread blackout in 2021, which was “attributed at the time to a technical fault in Pakistan’s power generation and distribution system,” AP writes.