March 18 (UPI) -- The U.S. National Highway Traffic Safety Administration is investigating several Hyundai and Kia vehicles after air bag failures caused deaths in multiple crashes.
The front air bags failed to deploy in six crashes, which resulted in a total of four deaths and six injuries, according to an investigation report by the Office of Defects Investigation.
Four of the crashes involved Hyundai Sonatas made in 2011 and the other two involved Kia Fortes made in 2012 and 2013.
Hyundai recalled nearly 155,000 Sonatas after determining electrical overstress caused the airbags to fail to inflate in three of the crashes.
The cause of the crashes is being investigate with the air bag control unit supplier ZF-TRW, which provides similar components to Hyundai and Kia.
"We are actively investigating what exactly causes the airbag control unit to become damaged in these specific types of accidents, but are announcing this recall now to ensure the safety of our customers," Hyundai said in a statement, according to Bloomberg.
Kia also issued a statement saying it "remains focused on the safety of its customers and it will work closely with NHTSA on the ongoing investigation, including monitoring and conducting additional crash testing as appropriate."
The NHTSA's investigation seeks to evaluate the scope of Hyundai's recall, confirm Kia's use of similar airbag control units, review the root cause analysis of all involved parties and review factors relating to the airbag control units or the vehicles that may be causing the failures.