Venezuela was hit by a new blackout on Monday, said reports on social networks.
The power outage affected much of the country (about 17 states) as of 4:40 p.m. local time (2040 GMT), including the capital district.
Officials blamed the power failures on sabotage by the far-right opposition, which masterminded several previous blackouts.
"The first indications received from the investigation point to the existence of an electromagnetic attack, which sought to affect the country's hydroelectric generation system, the main provider of power in Venezuela," said Minister of Communication and Information Jorge Rodriguez.
Authorities were working to restore services, he added.
The blackout has knocked out telecommunications and traffic, among other services, with many people posting images of Caracas residents walking to their destinations after subway services were interrupted.
Sporadic power outages are common in Venezuela, a country whose economy has collapsed amid a years-long political crisis.
Venezuelans still have fresh memories of a massive blackout on March 7 that brought the country to a standstill for days.