An Education Department employee was attending a funeral this week when she got the call: She was being placed on administrative leave because she works on projects that connect Black students, among others, to federal government programs.

A disabled veteran employed at the Department of Veterans Affairs grew emotional when he heard about the rescinding of telework options, unsure whether it would mean the end of his job taking care of fellow soldiers.

A Federal Trade Commission employee was so anxious that he told family members not to talk about politics on unencrypted lines. Across government agencies, workers eyed one another nervously, wondering whether a colleague would report them, accusing them of resisting the new administration’s move to end certain programs.

President Trump’s rapid push to overhaul the federal bureaucracy in his first days in office has been met with a mix of fear, fury and confusion throughout the work force.

Dozens of employees across the government, many of whom spoke on the condition of anonymity because of worries of retribution, described agencies gripped with uncertainty about how to implement the new policies and workers frantically trying to assess the impact on their careers and families. As the nation’s largest employer, the upheaval in the federal government could reverberate in communities throughout the country.

Starting on Inauguration Day, the orders and memos came down one after the other, many crafted in the pugnacious tone of a campaign speech: the shuttering of “Radical and Wasteful” diversity programs in federal agencies; the stripping of civil service protections from a share of the federal work force; the end to remote work, which, one administration memo claimed, had left federal office buildings “mostly empty” and rendered downtown Washington “a national embarrassment.”

All new hiring was frozen, job offers were rescinded, scientific meetings were canceled and federal health officials were temporarily barred from communicating with the public, a directive that some understood as so broad that it even extended to making outside purchase orders for lab supplies.

For the more than two million federal workers, roughly four-fifths of whom live outside the Washington area, change is inevitable whenever a new administration takes over. But few had expected it to come at this speed and scale.

“They are being upended in the most brutal and traumatic way imaginable,” said Max Stier, president of the Partnership for Public Service, a nonprofit that works to promote excellence and best practices in the federal government. Mr. Stier said he had deep concerns about the consequences of Mr. Trump’s swift changes on the ability of the country to face a range of threats, from terrorism to pandemics.

An ambition to change things is reasonable, he said. But “the speed is unnecessary and destructive,” he added.

Federal employees looked to their supervisors for guidance, but said they often had none to give, as they tried to interpret brief orders and memos with few specifics. For example, the return-to-office memo said employees with a disability could be exempt, but it was unclear what kind of disability might qualify. Some managers said they knew nothing beyond what was in the news. Adding to the panic were remarks by the president himself, who suggested on Friday that he might consider shuttering the Federal Emergency Management Agency, which employs 20,000 workers around the country.

A spokesperson from the Office of Personnel Management defended the actions in a statement, calling them “exciting steps to build a federal work force based on merit, excellence and accomplishment, so we can have a government that serves the public effectively and efficiently.”

“We have already saved millions of hard-earned taxpayer dollars that are no longer directed to DEIA programs that wasted millions of hard-earned taxpayer dollars and discriminated against federal workers,” the statement said, referring to diversity, equity, inclusion and accessibility efforts.

Donald F. Kettl, an emeritus professor at the University of Maryland who studies the civil service, said there was widespread consensus among experts that the civil service is in need of changes.

“It’s too hard to hire, it’s too tough to fire, and there’s too little match between the civil service system and the capacity government needs to handle 21st-century challenges,” Dr. Kettl said.

But he said that many of the Trump administration’s proposed changes would be counterproductive. “They’re focused much more on shifting the balance of power than they are on improving the results of government,” he said.

Inside federal offices, the mood has been tense and anticipatory. One employee at the Homeland Security Department said the staff felt at risk of being fired at any moment. At the Commerce Department, employees were terrified whenever a meeting was called, one worker said.

The isolation is deepened, some federal employees said, by the fact that most of their fellow Americans see the federal government as bloated and inefficient. Some said that reform, if it were well thought-out, would be healthy and welcome. But many noted that they had accepted significant pay cuts to work for the government because they believe in public service — issuing Social Security checks, keeping air travel safe and inspecting food, among other roles.

“The reality is that the American economy needs my agency’s work,” said Colin Smalley, a geologist with the U.S. Army Corps of Engineers and the president of his local of the International Federation of Professional and Technical Engineers. “We keep construction projects going, ports and waterways open, power grids functioning, and we protect communities from natural disasters and help affected communities recover. Hurting our mission hurts the public.”

Compounding the anxiety was a directive from the Office of Personnel Management instructing agency heads to turn over by Jan. 24 names of those who were still in their probationary period, typically within one or two years of their hiring.

The directive noted that such employees “can be terminated during that period without triggering appeal rights,” and that managers should determine whether they should be retained, according to a copy obtained by The New York Times.

Jacqueline Simon, the policy director for the American Federation of Government Employees, which has about 300,000 active members across dozens of agencies, said that attempts to terminate federal employees still in their probationary periods could have damaging effects on government services.

For example, she said, employees of the Food Safety and Inspection Service, who work in meat and poultry plants to prevent diseased animals and other contaminants from entering the food supply, frequently leave within a year because the job is so depleting.

“It’s not a job you stay in long,” Ms. Simon said, calling the work “dirty and dangerous.” If the Trump administration were to remove everyone in the service who was still on probation, she added, there would be a severe shortage of inspectors at meat processing plants.

An attorney at a federal enforcement agency said he works on a team of more than a dozen lawyers, more than half of whom are still in their probationary period. If the team were to lose all of its members still on probation, the attorney said, it would be “catastrophic” for the team’s ability to shoulder its law enforcement responsibilities.

One of the most sweeping changes made by Mr. Trump in his first week was to order federal workers back to the office full time by later next month, ending years of a flexible telecommuting policy, which in many offices dated to well before the pandemic. For some who want to keep working for the government, this could mean selling homes, changing children’s schools and moving hundreds of miles in a matter of weeks. New mothers are debating whether they will be able to return from maternity leave, and couples have been forced to choose who gets to keep their current jobs.

Many offices do not currently have enough room for all of the employees to come back. This, some contend, is the whole point. Shortly after the November election, Elon Musk and Vivek Ramaswamy, the men tapped by Mr. Trump to remake the government, wrote in a Wall Street Journal op-ed: “Requiring federal employees to come to the office five days a week would result in a wave of voluntary terminations that we welcome.”

“I think we know where it looks like he’s trying to go, which is to force people to quit,” said Representative Glenn F. Ivey of Maryland, a Democrat whose district is home to tens of thousands of federal workers. “They’re going to try and force a lot of federal employees out of work, and then replace them with political loyalists.”

The administration’s efforts are already being challenged in court by unions and other groups, who argue, among other things, that the lifting of civil service protections runs afoul of laws governing federal workers.

Among the first to feel the direct impact of the president’s new policies were employees working on diversity, equity and inclusion initiatives and programming. Mr. Trump ordered the immediate shutdown of all such offices, with their staff placed on administrative leave by Wednesday at 5 p.m. Agencies were ordered to draw up plans to lay them off by Jan. 31. The administration also threatened employees with “adverse consequences” if they failed to report on colleagues who defy the orders within 10 days, setting up a special email account for such reports.

The Education Department employee who was placed on leave while she was at a funeral said she had worked on an acclaimed program connecting students with scholarships and industry leaders, and helped Black people tap into government programs they often did not know existed. In various communications, the Trump administration has called such efforts “harmful” and “wasteful.”

“I guess if that’s harmful, then I’m proud of providing that harm — empowering the community to be better because we are brilliant,” she said. “We just don’t have the access to generational wealth and nepotism that they have, so we have to teach people how to make it for themselves.”

In a work force that is nearly 20 percent Black, many employees said there could be another consequence of the moves: making the federal government whiter and less diverse.

By the end of the week, some employees said wearily that they did not know how long they could hang on. Many described conditions as reminiscent of the McCarthy era, and were despondent to see how quickly their office’s leaders acquiesced.

At the Department of Labor, staff members watched a colleague who had been recently hired to a civil service position be escorted out because she was a former political appointee. One employee said her manager required her to scrub the website not only of the words “diversity, equity and inclusion,” as the executive order required, but also of references to “underserved” and “marginalized communities.” Afterward, she said, she went into a closet, called her mother and wept.

On Tuesday morning, Moriah Lee, an analyst at NASA, joined a virtual town hall to learn what all the orders would mean for her small team, which monitors and audits projects in the space program. The acting supervisors, people she had known personally for years, made it clear to everyone that they were not inclined to show flexibility, she said.

Gone was the weekly speaker series that had been organized under the diversity program, which had brought in deaf people, combat veterans and others to share their experiences. Gone was her ability to live in Nashville and go twice a month to an office two hours away in Huntsville, Ala.

After the meeting, she and her colleagues went back to their jobs. They were rattled, she said, but not afraid. “The people who are acting most in fear are the ones in authority,” she said.

But the change to remote work, combined with the other directives, was just too much for her. And so Ms. Lee sent in her notice: Nearly six years after she began working for the federal government, she was resigning.

Kate Kelly, Hamed Aleaziz and Sheryl Gay Stolberg contributed reporting from Washington.