Puerto Rico woke up in darkness on Tuesday morning, after a power grid failure left nearly all of the island without electricity.
Around 90% of clients on the island were without power at 9 am local time, according to energy distribution company Luma Energy's real-time portal.
It was not immediately clear what caused the collapse, though local media reported that a chain reaction began in the Guayanilla province on the southern coast.
A spokesperson for power generator Genera told local TV station WAPA that there was no estimate for when power could come back online.
Genera's website showed just one backup plant producing energy on the US territory.
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