The U.S. government is telling 3 million more vehicle owners to get their air bags repaired immediately because of potential danger to drivers and passengers, but the message has caused confusion about which vehicles are actually affected.

The National Highway Traffic Safety Administration is now warning 7.8 million car owners that inflator mechanisms in the air bags can rupture, causing metal fragments to fly out when the bags are deployed, according to the Associated Press.

Safety advocates say that at least four people have died from the issue, which they claim could affect more than 20 million vehicles around the nation. The inflators were made by supplier Takata Corp.

NHTSA's warning covers certain models made by BMW, Chrysler, Ford, General Motors, Mazda, Honda, Mitsubishi, Nissan, Subaru and Toyota.

"It's in a total state of uproar right now," said Clarence Ditlow, executive director of the Center for Auto Safety, a nonprofit advocacy group founded by Ralph Nader, according to the AP.

Most of the vehicles are subject to existing recalls, but automakers have limited the recalls to high-humidity locations, excluding cars and trucks in the north, according to the Associated Press.

NHTSA says owners in Florida, Puerto Rico, Guam, Saipan, American Samoa, the U.S. Virgin Islands, Hawaii and "limited areas near the Gulf of Mexico in Texas, Alabama, Mississippi, Georgia, and Louisiana" should pay special attention to the warning.

"It will aid in our ongoing investigation into Takata air bags and what appears to be a problem related to extended exposure to consistently high humidity and temperatures," said NHTSA Deputy Administrator David Friedman said in a statement, according to the AP.

Friedman added that the agency is tracking down the "full geographic scope" of the issue.

The safety administration has already twice corrected the number of vehicles affected and acknowledged that a list it released on Monday included some vehicles that aren't equipped with Takata air bags, while omitting others that actually have them.

Though people are being told to use the NHTSA website to decide if their vehicle is affected by the recall, the feature on the site to check for recalls by  vehicle identification number malfunctioned Monday night and still wasn't operational Wednesday.

Automakers have been recalling cars to fix the problem for several years, but neither Takata nor NHTSA have said what the issue is exactly. 

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