Research by the Wall Street Journal found that potentially explosive airbags are in 50 vehicle models across 15 brands, including Ford, Chevrolet and Hyundai.

The newspaper found a minimum of 6.8 million vehicles that automakers told U.S. regulators have the part in question as part of an eight-year investigation.

The number of effected vehicles should end up being far higher, though, as the National Highway Traffic Safety Administration has ordered parts manufacturer ARC Automotive to recall 67 million inflators used to fill airbags in a crash.

The airbags are prone to explosion in a collision, releasing shrapnel-like pieces of metal into the vehicle’s interior. At least two people have been killed and multiple others injured in such explosions, the newspaper said, citing the NHTSA.

ARC Automotive has said it won’t recall the part in question, denying that it’s defective.

The newspaper’s research found that General Motors apparently has the greatest number of vehicles with the potentially dangerous airbag part: a minimum of 3.6 million. GM has recalled four models, though the paper found that it has at least an additional 25 affected models that it hasn’t recalled.

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