SOUTH BEND, Ind. (AP) — The top U.S. environmental regulator says she wants to make sure Volkswagen's use of software in its vehicles to evade U.S. auto emissions limits was a "one-off," and other models will be tested aggressively to determine if other carmakers are trying to defeat pollution tests.

Gina McCarthy, Environmental Protection Agency administrator, responded to a question Friday during a news conference on global climate change at Notre Dame university.

"We're going to continue to aggressively pursue this issue with VW," she said.

And EPA would not stop there, she said. The agency would "look at all of the other models aggressively and do the testing we need" to foil any efforts to defeat the emissions system.

Earlier Friday, EPA announced plans for more robust emissions testing following the VW revelations.