HAVANA (AP) — Millions of people in Cuba were left without electricity for two days after the nation's energy grid went down when of the island's major power plants failed. The widespread blackout that swept across the county was the worst in years.

WHY DID THE GRID COLLAPSE? Cuba's electrical grid and oil-fired power plants are obsolete and crumbling, constructed decades ago and scarcely maintained. And because Cuba produces very little fossil fuel of its own - with limited refining capacity - it depends almost entirely on imports to assure adequate generation.

The national electrical system of Cuba suffered a total disconnection at 11 a.m. local time after a power plant failed, the Cuban Ministry of Energy and Mines said.

A growing energy crisis reached a crescendo Friday, as the country’s main power plant suddenly shut down, cutting off electricity to millions of Cubans.

After electricity was partially restored in Cuba following an island-wide blackout, the electrical grid collapsed a second time, causing widespread alarm. Journalist Ed Augustin told NBC News that while power is gradually being restored in some areas,

As electricity was being restored in parts of Cuba following an island-wide blackout, a total collapse of the electrical grid occurred once again.

Cuba’s electrical grid went down Friday after one of the island’s major power plants failed, a day after a massive blackout swept across the Caribbean island and with no official estimate for when service will be restored.