Puerto Rico has been plunged into darkness after an explosion and fire at an electric substation on Sunday caused a widespread blackout.
The Puerto Rico Electric Power Authority (PREPA) told the Associated Press that much of northern Puerto Rico, including parts of the capital, San Juan, as well as Guaynabo, Carolina and Juncos, remained without power in the wake of the explosion, but it hoped it would be restored within a day.
The blackout marks a setback in efforts to restore power to Puerto Rico, five months after Hurricane Maria wreaked widespread devastation and led to the longest blackout in U.S. history.
San Juan Mayor Carmen Yulin Cruz tweeted an image of a solar light following the blackout.
She also added an update on the fire, tweeting: “It appears fire has almost totally been extinguished and the cooling phase is beginning.”
PREPA officials told CNN that the fire had been caused by a mechanical failure.
Hurricane Maria hit Puerto Rico in September, causing homes to be flattened and a total blackout across the island. Puerto Rico’s power grid was already vulnerable; PREPA’s power plants were 44 years old on average, in contrast with the industry average of 18 years.
In December last year, TIME reported that the death toll on the island following the storm now exceeded 1,000 people.