The Trump administration’s mass layoffs across federal agencies have hit the Federal Aviation Administration (FAA), which has terminated over 100 probationary employees.

That includes some of those who work on the team responsible for producing air traffic navigation maps, multiple sources told ABC News.

The Professional Aviation Safety Specialists (PASS), which represents over 11,000 FAA employees, said 132 probationary employees were terminated.

“We believe all of these employees are critical not only to the frontline safety workers, but to the entire aviation ecosystem,” PASS National President Dave Spero told ABC News in a statement.

The FAA and the U.S. Department of Transportation have insisted no critical employees were let go.

Overall, the FAA employees about 45,000 people.

Some of the employees impacted were part of the FAA’s Air Traffic Organization (ATO) en route charting group, which is responsible for maintaining and updating Enroute Navigation Charts used in the National Airspace System and by air traffic controllers around the country, sources told ABC News.

Those terminations were communicated via email early Saturday morning.

“I was three weeks shy of my probationary employment with the FAA, and I received an email late Friday night into Saturday morning, outlining my termination effective immediately,” one of the FAA employees who was laid off told ABC News. “It was a shock given the fact how critical my position was with public safety, with air travel.”

The employee, who asked not to be named out of fear of retaliation, said that inside the FAA, there is “a lot of fear for public safety” given the layoffs.

“If we’re no longer there to create the maps that air traffic air traffic controls are using, mistakes will eventually happen,” they said.

According to the FAA website, the Air Traffic Organization is the “operational arm” of the FAA.

“It is responsible for providing safe and efficient air navigation services to 29.4 million square miles of airspace. This represents more than 17 percent of the world’s airspace and includes all of the United States and large portions of the Atlantic and Pacific Oceans and the Gulf of Mexico,” the website states.

Charles Spitzer-Stadtlander, who was an employee at the FAA’s National Defense Program and was also the FAA lead for open mission systems support replacement and the Hawaii National Defense Program, told ABC News that his termination caught him off guard.

He said that at the time of hiring, it was explained to him that he was required to work even during a government shutdown.

“My position was a public safety, national defense critical position, because I was required to work whenever there was a government shutdown,” he said, adding, “So when a government shutdown occurred, I was required to work because national security, national defense, public safety doesn’t care whether or not Congress can get its act together to actually pass a budget.”

Spitzer-Stadtlander told ABC that late on the night of Feb. 14, he was locked out of his work program and computer systems and, shortly after midnight, he received an email notifying him that he had been terminated.

“My immediate thought was that I had been hacked … It was nowhere on my radar that I was at risk of being fired,” Spitzer-Stadtlander said.

The email he received, viewed by ABC, stated: “DOT FAA finds that based on your performance you have not demonstrated that your further employment at the DOT FAA would be in the public interest. For this reason, the DOT FAA is removing you from your position with DOT FAA and the federal civil service effective today.”

Spitzer-Stadtlander said he had recently undergone a performance review where he received an “excellent” evaluation, and he had also been awarded a merit-based performance value for performance pay raise that was set to go into effect in the pay period he was fired.

He told ABC that he has retained counsel and plans to appeal the termination decision.

The FAA did not respond to ABC’s requests for comment on Spitzer-Stadtlander’s termination.