Takata Airbag Recall Questions Prompt DOT Investigation of NHTSA

— -- The Department of Transportation will conduct a review of the National Highway Traffic Safety Administration, which has been criticized for its handling of the Takata airbag recall this past week, as well as other recalls this year, a senior administration official told ABC News.

The airbags, made by Japanese auto supplier Takata, are blamed for at least three deaths and more than 100 injuries.

"The roll out of the safety advisory by NHTSA was not optimal, but what is most important right now is that a NHTSA-led investigation uncovered a very serious defect," a DOT spokesperson said. "Impacted vehicle owners should have their cars immediately checked by their manufacturers. This investigation is far from over and we will leave no stone unturned in the interest of public safety."

Regulators had allowed a recall limited to areas of the country with "high humidity," but some lawmakers are now calling for an immediate nationwide recall of millions of potentially faulty airbags.

"There needs to be a real overhaul of the National Highway Transit Safety agency," said Sen. Richard Blumenthal, D-Conn., one of the lawmakers who has criticized the limited recall.

"These exploding airbags can be killers," he said. "They literally have killed people."

Blumenthal said drivers should be given loaner cars to drive while the airbags are being replaced, to make it as easy as possible for people to get the work done.

"Disabling the airbags puts them in even greater danger so the only solution here is for a national recall with loaners provided to car owners at no cost to them," the senator said.

On Monday, the NHTSA published an urgent plea on its website for more than 4.7 million owners of vehicles with Takata airbags to immediately get the airbags replaced, as the owners had been directed in previous recall notices over the past two years.

Late Tuesday the government revised the number, however, saying actually 7.8 million vehicles have been subject to the airbag recall since 2013.

"The list below corrects the list that accompanied our October 20 advisory, which incorrectly included certain vehicles," the NHTSA website says, noting that the numbers could change again.

Beyond the list of make and models on the NHTSA website, the federal agency says concerned vehicle owners can contact their manufacturer's website to search by the vehicle identification number (VIN) to see if the vehicle they drive is one of those under recall. NHTSA has its own VIN lookup website, but as of this report, that function was unavailable due to "intermittent network issues," according to a posting on the site.

The recall reminder is "especially" urgent for vehicle owners in warm climates like the southern U.S., Hawaii and American island territories. Toyota, a maker of some of the recalled vehicles, said on its website Monday said the "influence of high absolute humidity" in the airbag malfunctions is under investigation.

Earlier this month Florida woman Hien Tran was killed in a mysterious auto accident that police initially treated like a homicide due to the apparent stab wounds on her neck. Later, however, investigators determined her fatal wounds were "consistent with… exploding airbags," according to The Orlando Sentinel. If confirmed, auto safety experts say Tran's death would be the fourth linked to the dangerous defect.

NHTSA opened an investigation into the issue back in June, at which time airbag supplier Takata published a statement on its website saying the company "is committed to the highest standards of safety for our customers – and their customers."

"For the past several months, we have been consistently cooperating with NHTSA, and we will continue to do so during the defect investigation that the agency recently opened, but we also stand by the quality of our products," says the note, which was reposted on Takata's website earlier this week. "Takata is committed to ensuring the safety and functionality of its airbag inflators, and we strive to avoid any malfunction."