Much of Venezuela remained engulfed by darkness into early Friday amid one of the largest power outages in years, raising tensions in a country already on edge from ongoing political turmoil.

The blackout hit 22 of 23 states by some accounts, striking the capital Caracas had been spared the worst of a collapse in the nation's grid, at the peak of rush hour.

Thousands of commuters flooded into the streets after subway service stopped. A snarl of cars jammed the streets amid confusion generated by blackened stoplights. Others had to walk long distances to get home.

At the darkened maternity ward at the Avila Clinic in wealthy eastern Caracas, several mothers cried as nurses holding candles monitored the vital signs of premature babies in incubators after backup generators shut off.

Venezuela's socialist government blasted the outage as an "electrical war" directed by the United States. Communications Minister Jorge Rodriguez said right-wing extremists intent on causing pandemonium in Venezuela and taking orders from Florida Republican senator Marco Rubio were behind the blackout, although he offered no proof.

"A little bit of patience," Rodriguez urged on state television, saying service would be restored in a few hours. "If you're in your home, stay in your home. If you're in a protected space or at work, it's better for you to stay there."

But as night wore on in Caracas, patience was running thin.

Residents threw open their windows and banged pots and pans in the darkness. Some shouted out expletives at President Nicolas Maduro in a sign of mounting frustration. Normally hyperactive social media was eerily silent as much of the country was knocked offline.

By midnight Friday, power had yet to be restored in Caracas and many other areas.

The outage comes as Venezuela is in the throes of a political struggle between Maduro and opposition leader Juan Guaido, the head of congress who declared himself the nation's rightful president in January and is recognized by the United States and about 50 nations.

Guaido took to Twitter to blast Maduro for the outage.

"How do you tell a mom who needs to cook, an ill person who depends on a machine, a worker who should be laboring that we are in a powerful country without electricity?" he wrote, using the hashtag (hash)SinLuz, meaning without light. "Venezuela is clear that the light will return with the end of usurpation."