More than a million customers in Puerto Rico are left in the dark after a fire at a main power plant caused a big blackout.

Some Long Islanders were on the island visiting relatives when it all happened.

Brentwood resident Ana Crespo was visiting her 79-year-old mother when "everything went black."

"It's very quiet," Crespo says. "So surprised, but everybody's inside their houses. People were not called in to go to work because there's no light."

Others like Central Islip resident Margarita Espada is worrying from afar.

She says she wasn't able to get in contact with her elderly mother and stepfather until Thursday.

"There's no communication so my heart jumped," Espada says.

Espada's stepfather Jose Martinez expressed his frustration with Puerto Rico's aging electricity system, which was battered by Hurricane Maria in 2017.

Luma Energy, which runs Puerto Rico's power grid, says crews are working nonstop to restore service.

The blackout also left around 160,000 customers without water and caused traffic jams across Puerto Rico.