Sen. Bill Nelson (D-Fla.) holds of a piece of shrapnel from a Takata airbag during a Senate Commerce, Science and Transportation Committee hearing on Capitol Hill in Washington on June 23, 2015. (Susan Walsh/AP)

Auto parts giant Takata ignored deadly air-bag flaws and skipped global safety checks to save money in the years before the largest U.S. auto recall was launched, according to a congressional report cited during a hearing Tuesday into the defect that has left eight dead and more than 100 injured.

But lawmakers at the Senate Commerce, Science and Transportation Committee hearing focused their anger not just on Takata, but on federal safety regulators, who were criticized in a scathing Transportation Department inspector general’s audit for failing to protect drivers from disastrous defects.

“This isn’t about resources. This is about blatant, incompetent mismanagement,” said Sen. Claire McCaskill (D-Mo.), who called the Transportation Department IG’s audit of the National Highway Traffic Safety Administration “one of the worst I’ve ever seen.”

“If NHTSA doesn’t know when an investigation should be opened, we might as well shut it down,” she added.

After months of testing, investigators have yet to identify a root cause for the Takata recall, which now includes about 34 million defective air-bag inflators in 32 million vehicles made by about a dozen of the world’s largest automakers.

On Friday, an eighth death was conclusively tied to a faulty Takata air bag, which inflate with so much force that they blast out metal shards: a 26-year-old woman who rented a 2001 Honda Civic from a San Diego rental outlet, even though the car had been repeatedly recalled.

Takata, one of the world’s biggest air-bag makers, was lambasted in the report issued by the Commerce, Science and Transportation Committee’s Democratic minority, led by Sen. Bill Nelson (Fla.). Internal company e-mails “suggest that Takata may have prioritized profit over safety by halting global safety audits for financial reasons,” the report said.

The Japanese auto parts supplier, the report said, knew of quality-control gaps in manufacturing as early as 2001 and at least three incidents involving faulty air-bag parts by 2007. Yet the first and smallest recall was not launched until 2008, and Takata fiercely resisted an expanded recall that would cover millions of additional defective cars.

In one 2011 e-mail exchange quoted in the report, a supervisor at a Takata plant in Mexico told a quality engineer about inflators that were not properly welded: “We cannot be faced with findings/defects of this sort and NOT do ANYTHING. . . . A part that is not welded = one life less, which shows we are not fulfilling the mission.”

The engineer agreed, saying “we are in a very critical situation because of the most recent problems that we have detected on the line. . . . Situations like this can give rise to a Recall.” Nevertheless, quality-control problems continued.

Displaying a jagged chunk of metal that blasted out of an air bag and bloodied a Miami driver, Nelson said: “This is deadly serious business. . . . For years, Takata did not put safety first.”

Takata’s North American executive vice president, Kevin Kennedy, disputed the report’s findings, saying that the internal e-mails were misconstrued and that routine audits of product safety and quality were never paused.

Asked by Sen. Richard Blumenthal (D-Conn.) whether Takata would establish a victims’ compensation fund similar to the General Motors fund covering ignition-switch defects, Kennedy said that Takata would deliver an answer within two weeks.

Even without the fund, the Japanese firm is facing huge financial hits. A Fiat Chrysler executive said Tuesday that the carmaker would replace all recalled Takata driver-side air-bag inflators, in vehicles such as the Dodge Ram and Chrysler 300, with new parts from TRW Automotive, the biggest shift yet from a large automaker to one of Takata’s rival manufacturers.

When pressed, the Fiat Chrysler executive said that the firm had switched suppliers because the firm had more confidence in the parts made by other manufacturers.

Lawmakers said they were worried about the possibility that many more Takata deaths and injuries have yet to be discovered. Blumenthal compared the eight confirmed Takata deaths to those from General Motors’s ignition defects, which early estimates suggested had killed about a dozen people. The confirmed death count has since risen to 117.

Meanwhile, many of the defective cars remain on the road while automakers struggle to get enough replacement parts. Takata has so far produced 5 million replacement kits, less than a sixth of the number needed, and executives expect the firm to be able to manufacture only a million replacement parts a month.

A Honda Motor executive at the hearing said that the company’s vehicles were averaging more than 50,000 air-bag repairs a week, adding that company dealers were authorized to give rental cars to drivers whose recalled cars were undergoing repairs.

Many vehicles have been given temporary air-bag fixes but will need further repairs.

Takata said that it continues to use a chemical, ammonium nitrate, in its air bags to hurry along repairs, even though some experts have said that the propellant is unsafe.

Some senators agreed with NHTSA Administrator Mark Rosekind’s insistence that the agency needed more money to manage an “overwhelming” flood of potential investigations and complaints. But lawmakers from both parties said that they would demand more far-reaching reforms before agreeing to invest more in the federal watchdog.

“I’m not about to give you more money until I see meaningful progress,” McCaskill said.