SAN JUAN, Puerto Rico (AP) — A widespread power outage hit Puerto Rico Wednesday night, leaving more than 340,000 customers without electricity after two of the U.S. territory’s power plants shut down.

The capital of San Juan was left without power, as well as neighboring municipalities including Bayamón, Caguas and Carolina.

Luma Energy, which operates transmission and distribution for Puerto Rico’s power authority, said on X that the outage was tied to an issue with the power plants’ transmission lines. It provided a statement to The Associated Press saying it was investigating the outage that coincided with the shutdown of units operated by GeneraPR, which operates and maintains state power generation units.

The outage is the most recent in a string of blackouts to hit Puerto Rico, which is still trying to rebuild the grid after Hurricane Maria razed it in 2017 as a Category 4 storm.

The outage prompted the mayor of the San Juan capital, Miguel Romero, to declare a state of emergency late Wednesday as he accused Luma of sharing limited information about the ongoing blackouts.

“There are thousands of children with specific feeding needs, as well as older adults who often need therapy machines to protect their health and often save their lives,” the decree stated.

Scores of Puerto Ricans took to social media to condemn the most recent outage and demand the ouster of Luma, noting that it occurred amid excessive heat warnings. Not all on the island of 3.2 million people with a poverty rate of more than 40% can afford generators or solar panels.