Buenos Aires - The president of the Center for the Study of Energy Regulatory Activity in Argentina says that a massive blackout that left millions without electricity “has never happened” in the country.

Raúl Bertero is a professor at the University of Buenos Aires. He said Sunday that systemic operational and design errors played a role in the power grid’s collapse.

“A localized failure like the one that occurred should be isolated by the same system,” he said. “The problem is known and there is technology and studies that (work to) avoid it.”

He also said that independent experts should be asked to determine what happened.

The failure left many in Argentina, Uruguay and Paraguay without electricity for hours.