Federal prosecutors have launched a probe into whether Japanese airbag manufacturer Takata Corporation misled U.S. regulators about the safety of its products after faulty airbags were implicated in the deaths of at least two people, according to a report. U.S. auto safety officials have now recalled nearly 8 million cars with Takata airbags.

The probe into Takata’s statements is exploratory in nature and will not necessarily result in charges, sources familiar with the situation told the Wall Street Journal. The Manhattan U.S. attorney’s office will spearhead the investigation, which will proceed without interruption to the scheduled Takata airbag recall.

Takata has yet to comment on the probe. Several major car manufactures are Takata customers, including Toyota Motor Corporation and Honda Motor Co. Ltd., Reuters notes.

The National Highway Traffic Safety Administration announced Tuesday that the Takata airbag recall would be expanded to include at least 7.78 million vehicles, USA Today reports. The announcement marked a dramatic increase from an airbag recall issued Monday that extended to 4.74 million vehicles. The faulty airbags pose an imminent danger to affected drivers, who were told to have their vehicles repaired “with urgency.” The replacement of Takata airbags is “essential to personal safety,” the NHTSA said.

Senators Richard Blumenthal, D-Conn., and Edward Markey, D-Mass., criticized the NHTSA Wednesday for limiting the recalls to so-called high-humidity areas. Humidity can cause the airbags to explode, spraying front-seat passengers with shrapnel. A previous airbag recall that affected more than 3 million vehicles in June focused primarily on vehicles registered in high-humidity states and territories.

“NHTSA should immediately issue a nationwide safety recall on all the affected cars, regardless of where the car is registered,” the senators wrote in a letter addressed to Transportation Secretary Anthony Foxx, according to the New York Times. “All states experience seasons of heat and humidity.”

A shortage of the parts necessary to fix the faulty airbags has led some costumers to delay or ignore the recall, the newspaper said. Toyota has ordered the disabling of airbags that cannot be immediately replaced -- a policy that “alarmed and astonished” Blumenthal and Markey.

“If a replacement part is temporarily unavailable at the time of repair, we view disabling the front passenger airbag as a temporary measure that prioritizes customer safety,” said Toyota spokeswoman Cindy Knight in an email to the New York Times. “We also advise that customers not occupy the front passenger seat until the replacement inflator is installed and the airbag is fully functional.”