A massive electrical failure has left almost all of Argentina and Uruguay without power, according to a major Argentine electricity provider.
Authorities say the cause of the blackout is still unclear.Argentine media said the power cut occurred shortly after 07:00 (11:00 BST), causing trains to be halted and failures with traffic signalling.
It came as people in parts of Argentina were preparing to go to the polls for local elections.
"A massive failure in the electrical interconnection system left all of Argentina and Uruguay without power," electricity supply company Edesur said in a tweet.
Alejandra Martinez, a spokeswoman for the company, described the power cut as unprecedented.
"This is the first time something like this has happened across the entire country."
Argentina's energy secretary, Gustavo Lopetegui, said the cause of the power failure had not yet been determined. The Ministry of Civil Protection estimated that parts of the service could be restored in about seven or eight hours.