As part of an agreement with Takata, federal regulators expanded the recall of vehicles equipped with the company's air bags to 33.8 million in the U.S., making it the largest safety recall in the nation's history, reports Detroit Free Press.

The move essentially doubles the number of vehicles being recalled to replace potentially lethal air bags made by the Japanese supplier. At least six people have died and more than 100 have been injured from shards of metal from exploding air bags.

Takata, for its part, officially acknowledged the defects for the first time on Tuesday, even though 17 million vehicles with its air bags already have been recalled.

Mark Rosekind, recently appointed administrator of the National Highway Traffic Safety Administration, said no one knows how long it could take to fix the vehicles, but "it could take some years. ... We intend to make sure at the end of this process there is a safe airbag in every vehicle."

The NHTSA recall now involves 11 automakers, including the Detroit Three, most affecting 2002 through 2008 model years. Takata is partly owned by Honda, which has the highest percentage of recalled vehicles. The total number could change as automakers sift through the specs of all of their models to determine which ones contain any of the four defective inflators, which activate the air bags in a collision.

Many consumers will have to drive their vehicles for a long time before the parts are available to fix them, with the industry unable to manufacture replacement bags fast enough. They could also be waiting months for the notification their vehicle is subject to recall because automakers must prioritize vehicles at most risk based on their age and geographic location

The announcement is the second example in as many days of Rosekind cracking down on automakers to address safety on U.S. roads. On Monday, Rosekind announced he has scheduled a hearing in July for Fiat Chrysler Automobiles to explain their slow response in completing repairs in 20 different recalls.

NHTSA has been pushing for Takata to expand its air bag recall. Automakers had recalled about 17 million vehicles, many of them from Honda. The latest move largely makes this a national recall of vehicles from 11 automakers with vehicles that potentially have faulty inflators in the driver or passenger-side air bag.

"Up until now Takata has refused to acknowledge that their airbags are defective, that changes today," said U.S. Treasury Secretary Anthony Foxx. "Takata has agreed to declare their air bag inflators are defective."

Takata Chairman Shigehisa Takada, in a statement, said, "We are pleased to have reached this agreement with NHTSA, which presents a clear path forward to advancing safety and restoring the trust of automakers and the driving public."

The supplier has also agreed to enter into a consent order with NHTSA to supply all related documents and information about the defective airbags and pledged full cooperation going forward.

In return, NHTSA has suspended more than $1 million in accumulated fines -- $14,000 per day since February -- for not responding to all NHTSA's inquiries. The agency has not ruled out more fines in the future and there could be further civil penalties.

Initially the exploding air bags were considered a problem only in hot and humid climates but the recall has been expanded nationally as Takata and affected automakers continue to try to identify the root cause of the problem so they can fix it.

The recall has also expanded to cover both driver and passenger side air bags in more vehicles and regions.

Automakers with affected vehicles include Honda, Toyota, Ford, BMW, Fiat Chrysler Automobiles, General Motors, Mazda, Mitsubishi, Nissan, Subaru and the newly added Daimler Trucks. The automakers formed a coalition and hired independent engineering firm Orbital ATK to try to find the cause of the exploding air bags. Their investigation is in addition to those being conducted by NHTSA and Takata in an industry-wide effort to find the reason for the defect to make sure it is fixed properly.

NHTSA also is opening its own testing program to focus on ensuring the remedy is completely safe. Rosekind said while the replacement air bags are safer than the ones they replace, he cannot guarantee their long-term safety at this time.

"We are doing our best to keep focused on the investigation," said former NHTSA Administrator David Kelly who was hired to oversee the investigation by the automakers. Efforts to determine the root cause are still in the early stages of testing, he said.

Safety officials warn consumers to keep checking their vehicle VIN number on the www.safercar.gov website because even some of the vehicles previously fixed - or excluded in the past -- could be back on the recall list in the future.

Consumer who receive recall notices should call their dealer immediately.

"Folks shouldn't have to drive around wondering if their airbag is going to explode in their face or if their car is going to be on another recall list," said U.S. Sen. Bill Nelson, D-Fla., the top Democrat on the Senate Commerce Committee and a key figure in a congressional probe into the defective airbags. "We've seen the recall list double now to 30 million cars. Let's hope Takata's admissions today tells us the whole story."

Rich Newsome, an attorney representing seven victims of faulty Takata air bags, including Corey Burdick, a Florida man disfigured and blinded in one eye by shrapnel from an exploding air bag in May, called it a victory for consumer protection.

But, he said, "today's expanded recall is already too little, too late for people injured and their families. Hopefully today's news will push the agenda for recall reform to the forefront and result in legislation that will help NHTSA identify these kinds of defects before regular families with defective cars are needlessly harmed in the future."

Automakers say they will continue to work with NHTSA and share test results. Honda said many of the recalls announced Monday already were included in previous safety campaigns and the automaker is "reviewing the information released (Monday) to determine what new actions may be required."

Honda owners can check their recall status at www.recalls.honda.com or call 800-999-1009. Acura owners should go to www.recalls.acura.com or call 800-382-2238 and press option 4.

"A recall of this scope illustrates the potential for massive automaker expense and consumer inconvenience when a common, mass-produced part is defective," said Karl Brauer, analyst with Kelley Blue Book.

"While this is the largest consumer recall in history it's likely we'll see future vehicle recalls of similar, if not larger, size as the automotive industry becomes more globalized." Brauer said.

Takata boosted production to 450,000 replacement kits per month in March, up from 350,000. Other suppliers are also ramping up capacity to meet the demand the recall has created as the industry works to address the problem collectively.

Autoliv, another global supplier of airbags, said Tuesday it could make more airbag inflators than it has already promised to the industry.

In January, Autoliv committed to providing several automakers with as many as 25 million airbag inflators and could begin delivering them later this year.

"Our focus has really been to help the industry and the customers in this situation and clearly if we would be asked to supply more we would work to do that as rapidly as we could," said Thomas Jonsson, spokesman for Autoliv.