NEW YORK, United States (AFP) — US car safety regulators have broadened a probe of ZF-TRW airbags used on some 12.3 million vehicles following as many as eight fatalities, documents showed Tuesday.

Investigators are expanding the probe to include six manufacturers who use the airbags, which could fail during a crash, according to a notice on the National Highways Traffic Safety Administration’s website.

The probe, which centers on various models made between 2010 and 2019 of Kia, Mitsubishi, Honda, Hyundai, Toyota and Fiat Chrysler, will determine whether “an unreasonable risk exists that requires further action,” NHTSA said.

Hyundai-Kia and FCA have undertaken voluntary recalls for the defect but NHTSA could also mandate a broader recall.

The airbags were made by US supplier TRW, which was acquired by German company ZF in 2015.

The move came after investigators studied two serious frontal car crashes on Toyota Corollas in which the airbags did not deploy, resulting in one fatality, the notice said.

The investigation has centered on problems with an electric component that monitors signals from crash sensors.