Takata Industries, the maker of the defective airbag parts being recalled. affecting nearly 8 million cars, is now the subject of a preliminary criminal investigation by federal prosecutors in New York.

The problem with the airbags - made at plants in Washington state and Mexico - is that the defective inflator can explode with too much force, shattering the metal into shards that, car safety advocates say, are believed to have killed four people.

Investigators are looking into whether Takata provided misleading information to federal safety regulators.

Related: Feds say millions more airbags could be dangerous. Related: US urges car owners to "take immediate action" on airbags. Related: Senators seek national airbag recall.

Already, the National Highway Traffic Safety Administration has said that there are not enough replacement inflators for the nearly 8 million cars recalled.

It said it has been in contact with Takata to try to expand production of replacement units and has asked the company to look at outside sources to help boost production.

Takata has said it is "cooperating" with the recall.

BMW and Honda, two of the 10 companies recalling bags, have said that customers will have to wait for a replacement.

Toyota said that it would disable passenger airbags if it couldn't get replacement airbags, which is not in violation of any law, according to the NHTSA. Consumers have been left confused as to what to do next.

On the NHTSA website, consumers can find a list of makes and models and search by vehicle identification number to see whether their car is one of those under recall.

The federal agency also said vehicle owners could check their manufacturer's website to search by the VIN.