Story highlights "Western Cuba is without power," a pro-government blogger says

Residents in Havana and elsewhere in Cuba suddenly lost power around 8 p.m.

A government spokesman says Havana is in the dark, except those with generators

Residents elsewhere on the island say they have no power, though some do

Millions of people suddenly lost power Sunday night around the island of Cuba -- including all of Havana.

More than 2 million residents of the capital were in the dark late Sunday, except for those at hospitals and elsewhere with generators, according to a government spokesman, who was not identified per government policy. The streets of Havana lost electricity around 8 p.m.

Residents elsewhere around the Caribbean nation -- including in Ciego de Avila to the east of Havana, and west to Pinar del Rio -- also told CNN they didn't have any power, except for a few pockets of light.

"Western Cuba is without power," a pro-government blogger known as Yohandry Fontana tweeted.

Power outages are hardly unprecedented in Cuba, which has an aging power grid. But while brief outages concentrated in a small area are common -- unless, of course, a big storm passes through -- a massive outage on this scale is rare.

There was no official explanation for Sunday's outage, according to the government spokesman and state media reports.

Weather reports for Havana indicated partly cloudy conditions on Sunday night with temperatures in the high 70s. Temperatures were forecast to hover around 90 degrees Fahreinheit on Monday, according to multiple sources.