A massive electrical failure has hit Argentina and Uruguay countries according to a major electricity provider.
"A massive failure in the electrical interconnection system left all of Argentina and Uruguay without power," electricity supplier company Edesur said in a tweet.
It was also reported the power cut had affected parts of Brazil and Paraguay.
There are about 48 million people in both countries and people in some parts of Argentina are preparing to go to the polls for local elections.
Argentine media said the power cut shortly after 7am local time and caused trains to halt as well as failures to traffic signalling.
The cause of the outage was still unclear, but the Argentina energy agency said in a statement that authorities were working to restore power to provinces in the northwestern corner of the country.
Several major cities, including the Argentine capital of Buenos Aires, awoke to darkness on Sunday morning, with public transportation brought to a halt by the outage.
Total recovery was estimated to take a few hours, according to the Energy Secretariat.
A spokesman for Brazil´s power system operator said the outage had not impacted the regional neighbor to the north.
