A fire that broke out at the Costa Sur power plant in Puerto Rico late Wednesday forced an island-wide outage, the biggest blackout this year so far due to an ailing electric grid. Power may not be restored to some parts of the island until Friday, according to Puerto Rico’s electricity grid operator.

The exact cause of the fire remains unclear, but it began around 8:45 p.m. on Wednesday at the power plant located just outside the town of Guayanilla on the southwest coast. It cut power across the island, where more than a million people are still without electricity.

About 160,000 people were also left without water, according to NBC News. So far, power has been restored to about 80,000 of the island’s 1.4 million energy consumers, according to government officials.“The system is being restored little by little,” Kevin Acevedo, a vice president of Luma, told the Associated Press. “The people of Puerto Rico have to understand that it’s a system with a lot of years. Bringing back Puerto Rico’s system is a delicate and complicated process.” read more below

Island-Wide Blackout Sweeps Puerto Rico After Power Plant Fire