Caracas and other parts of crisis-wracked Venezuela were hit by a massive power cut on Monday that the government blamed on an "electromagnetic attack".
The lights went out in most of Caracas at 4.41pm GMT while people in other parts of the country took to social media to report their own power outages.
"The first indications received from the investigation... point to the existence of an electromagnetic attack that sought to affect the hydroelectric generation system of Guayana," Communication Minister Jorge Rodriguez said on state television.
Guayana in southern Venezuela is home to the Guri hydroelectric power station that produces 80 per cent of the country's electricity.
Mr Rodriguez recognised the cut as a "national event".
The capital was hit by a massive gridlock as traffic lights lost power and sidewalks teemed with pedestrians walking home after the metro stopped running.
Closed stores were a common sight on Monday, as the lack of electricity prevented the use of credit and debit cards, which are essential due to the shortage of cash in inflation-plagued Venezuela.
"I'm hungry, I want to eat, but there is nowhere to use my debit card," said Hernan Montalvo, complaining of not having enough cash to buy a hot dog.
By late evening, Caracas was cloaked in darkness, its streets empty and barely illuminated by the headlights of the occasional passing car.
"I'm outraged," Eurimar Guere, 36, said after leaving her office in eastern Caracas.
"Necessary repairs weren't carried out and it's more of the same. Maybe this power cut will be worse than the previous ones."
President Nicolas Maduro denounced what he said was a "criminal attack against the tranquillity and peace of the homeland", adding that the country's armed forces had been deployed for relief efforts.
A major power outage in March affected all 23 states in Venezuela and lasted a week, paralysing basic services such as the water supply and forcing the offices and school to close.
Hospital care was also affected by that incident and another one that came days later.
Opponents of Mr Maduro said at the time that about 20 people died due to problems receiving medical treatment because of the blackout.
Mr Maduro had blamed unnamed "terrorists" for that near-nationwide blackout, claiming they had attacked the Guri hydroelectric plant.
Another huge outage in April left large parts of the country, including Caracas, in darkness, although it lasted hours rather than days.
Mr Rodriguez said that following the earlier blackouts, the government "has implemented protection and security protocols" that will permit the restoration of electricity "in the shortest possible time."
Blackouts are a common occurrence in Venezuela, especially in remote western regions.
The government usually blames them on sabotage but experts say that a lack of investment, poor management, the emigration of qualified engineers and personnel, and corruption are the more likely culprits.
"They tried to hide the tragedy by rationing throughout the country, but the failure is clear," wrote opposition leader Juan Guaido on Twitter.
"They've destroyed the electricity system and they don't have any answers."
Crisis-wracked Venezuela has been mired in a political impasse since January when Mr Guaido proclaimed himself acting president, quickly receiving the support of more than 50 countries.
The oil-rich, cash-poor country has been in a deep recession for five years. Shortages of food and medicine are frequent, and public services are progressively failing.
Around a quarter of Venezuela's 30-million-strong population are in need of aid, according to the United Nations. Three million people have left the country since the start of 2016.
