The US agency that regulates the auto industry has laid off 4% of its staff, it said Monday.

The layoffs at the US National Highway Traffic Safety Administration are part of a broad effort by the Trump administration to cull the federal workforce.

The cuts worry safety advocates, who fear there could be an increase in car crashes with fewer regulators overseeing automakers.

The safety groups have raised also concerns about what happens to the agency’s ongoing probes, which include reviewing the safety of Tesla Inc.’s cars and driver assistance software. Elon Musk, who’s spearheading President Donald Trump’s push to shrink the federal workforce, is the chief executive officer of Tesla.

“Public safety should never be threatened at the political chopping block, particularly when clear conflicts of interest are in play,” Michael Brooks, executive director of the Washington-based Center for Auto Safety, which advocates for stringent regulation.

A NHTSA spokesman said even with the cuts, the agency has “retained positions critical to the mission of saving lives, preventing injuries, and reducing economic costs due to road traffic crashes.”

“The last administration grew NHTSA by a whopping 30%,” the agency spokesman said. “Even with these modest efficiencies, NHTSA is still considerably larger today than it was four years ago.”

NHTSA had 805 employees in fiscal 2024, according to a budget document submitted to Congress, up from 675 in 2023. US Department of Transportation Secretary Sean Duffy told Fox News on Monday that he had instructed DOT employees to reply to an email sent by the Office of Personnel Management at the behest of Musk asking federal workers to detail what they accomplished last week or risk being fired. Other agencies have instructed their employees not to respond until they received further guidance.

“If you can’t come up with five things you did, maybe you shouldn’t be employed here,” Duffy said in the interview. “I mean this is an easy task. It happens in the private sector all the time, and so I wanted our employees to actually engage and talk about what they did.”