Hospitals struggled to get backup generators running, businesses shuttered and families anxiously tried to contact loved ones amid Venezuela's worst-ever power outage Friday, raising tensions in a country already on edge from ongoing political turmoil.

Much of the nation of 31 million people was still without electricity as the blackout stretched into a second day and patience began to wear thin.

"This has never happened before," a frustrated Orlando Roa, 54, said, decrying President Nicolas Maduro's administration for failing to maintain the electrical system and letting qualified engineers leave the country. "This is the fault of the government."

Maduro ordered schools and all government entities closed, and told businesses not to open in order to facilitate work crews trying to restore power.

The Canadian Embassy in the capital, Caracas — closed on multiple occasions during the country's recent weeks of political crisis — was again closed on Friday.

The blackout hit 22 of 23 states by some accounts. It struck Caracas, which until now has been spared the worst of a collapse in the nation's grid, at the peak of rush hour late Thursday.

People cross a street during a power outage in Caracas on Thursday. (Yuri Cortez/AFP/Getty Images)

Thousands of commuters flooded into the streets because subway service was 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.

Pro-government state broadcaster VTV around 2 p.m. local time on Friday reported that electricity had been restored to 16 neighbourhoods around Caracas.

That account could not be immediately verified, though some Venezuelans on social media began reporting they had power.

Government claims sabotage

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 Sen. 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 the blackout wore on in Caracas, patience was running thin.

People queue for gasoline at a gas station Friday with power still out in Caracas. (Yuri Cortez/AFP/Getty Images)

With normally hyperactive social media eerily silent, residents threw open their windows and banged pots and pans in the darkness, shouting expletives at Maduro in a sign of mounting frustration. Even state TV — the government's main vehicle for handing down a political line to its followers — went silent.

Those lucky enough to have a battery-powered radio lying around tuned in to the few networks still operating, although information remained scarce.

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

Carlos Ramos, a Caracas resident, stood outside the hospital early Friday along with medical staff and patients in the fading hope he'd be able to see a doctor. He rejected the government's assertion of sabotage.

"They always say that," Ramos said.

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, Canada, and about 50 nations.

'Light will return with the end of usurpation'

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 labouring that we are in a powerful country without electricity?" he wrote, using the hashtag #SinLuz, meaning without light.

"Venezuela is clear that the light will return with the end of usurpation."

Venezuela's electrical system was once the envy of Latin America but it has fallen into a state of disrepair after years of poor maintenance and mismanagement. High-ranking officials have been accused in U.S. court proceedings of looting government money earmarked for the electrical system.

While intermittent outages have become regular occurrences in Venezuela of late, rarely have so many states simultaneously been without power for such an extended period.

Journalists use their smartphones during the blackout on Thursday. (Matias Delacroix/AFP/Getty Images)

While authorities expressed concern about the sick and elderly, and a few people had to be rescued from elevators, some residents in Caracas expressed awe at the sight of stars hanging over the normally bustling city of two million.

The government keeps home power bills exceptionally low — just a couple dollars a month — relying heavily on subsidies from the Maduro administration, which is under increasing financial duress.

The nation is experiencing hyperinflation projected to reach a mind-boggling 10 million per cent this year, is grappling with food and medical shortages and has lost about 10 per cent of its population to migration in the past few years. Venezuela's economic woes are likely to increase as U.S. sanctions against its oil industry kick in.

State-owned electricity operator Corpoelec blamed the outage on act of "sabotage" at the Guri Dam, one of the world's largest hydroelectric stations and the cornerstone of Venezuela's electrical grid.

Rodriguez described it as a "cyber" attack intended to derail the whole system. He said electricity in Venezuela's eastern region had been restored within two hours.

People queue up to charge their phones early Friday as power remained out across much of the country. (Carlos Jasso/Reuters)

"What's the intention?" he said. "To submit the Venezuelan people to various days without electricity to attack, to mistreat, so that vital areas would be without power."

Pro-government officials often blame power outages on Venezuela's opposition, accusing them of attacking power substations with Molotov cocktails, though they rarely provide any evidence.

Rubio, who has helped drive the Trump administration's confrontational stance toward Maduro, seemed to relish Rodriguez's accusations that he was somehow to blame for the power crisis.

"My apologies to people of Venezuela," the Florida Republican said in a message on Twitter. "I must have pressed the wrong thing on the 'electronic attack' app I downloaded from Apple. My bad."