Power station blast plunges country into darkness

The state electric power authority (AEE) said the blast was caused by a broken-down switch in Rio Piedras, resulting in a blackout in central San Juan and Palo Seco in the north.

"We have personnel working to restore the system as soon as possible," the AEE said.

San Juan's mayor, Carmen Yulin Cruz, said on Twitter that emergency services and local officials attended the scene in the neighborhood of Monacillos, but no injuries were reported.

Meanwhile, the Puerto Rican capital's airport said it was maintaining its schedule using emergency generators.

The blackout comes as nearly 500,000 of AEE's 1.6 million customers remain without power since Hurricanes Irma and Maria struck the US territory in September 2017.

AEE engineer Jorge Bracero warned on Twitter that the outage was "serious," and advised those affected that power would not be restored until Monday.