General Motors has been hit with a class-action lawsuit accusing the company of using defeat devices on hundreds of thousands of trucks equipped with diesel engines.

The suit was filed by the Hagens Berman law firm and alleges 705,000 Chevrolet Silverado and GMC Sierra models equipped with Duramax diesel engines used defeat devices to cheat on emissions tests. The suit covers trucks from the 2011-2016 model years and claims they emit between two and five times as much nitrogen-oxide as allowed by law.

The managing partner of the Hagens Berman law firm, Steve Berman, told The Detroit News “We have been systematically going through diesel cars made by all manufacturers since Volkswagen’s scandal came out. That led us to Mercedes, that led us to FCA and now we’re adding GM to the list of cheaters.”

General Motors reacted quickly to the lawsuit and released a statement saying “These claims are baseless and we will vigorously defend ourselves.” The automaker added, “The Duramax Diesel Chevrolet Silverado and GMC Sierra comply with all U.S. EPA and CARB emissions regulations.”

The news comes just two days after the United States Department of Justice and the Environmental Protection Agency filed suit against Fiat Chrysler Automobiles. In that case, the government alleges 104,000 Jeep Grand Cherokee and Ram 1500 vehicles equipped with the company’s 3.0-liter diesel engine have “software functions” that were not disclosed during the certification process. The lawsuit also says the company used a defeat device to deceive regulators.

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