Millions of people have been left in dark as a blackout hit at least four Central American countries.
Honduras was the hardest hit by the electrical grid failure, with all its territory and more than nine million inhabitants affected.
Traffic backed up as more than 600 stop lights went dark in the capital, Tegucigalpa, on Monday.
Salvador Mansell, president of Nicaragua's state power transmission company Enatrel, said the blackout hit his country's capital Managua and its main provinces.
There are about 600,000 paying customers for electricity in the country.
Internet service and water distribution in parts of the capital, which relies on pumps, were also knocked out.
El Salvador and Guatemala also had partial outages.
The four nations plus Costa Rica and Panama have shared a linked electrical network since the late 1980s.
Leonardo Deras of the state electric company said at a news conference the problem arose from an overload at a substation on the Caribbean coast.
Power began to be restored in the afternoon but Honduras's government said the process would take three or four hours.