At a barbershop in Los Angeles, only one of the 10 chairs was occupied on what would ordinarily be a busy evening.

In San Francisco, a middle school student’s erroneous information about seeing an immigration officer on a city bus prompted the school district to send parents a warning.

At a church in Charlotte, North Carolina, more than a third of the usual congregants were absent from a recent evening service.

Hotlines set up by advocates for immigrants to report enforcement activity have experienced a spike in calls.

“The hysteria is out of control,” said Patrick Garcia, executive director of Embrace All Latino Voices, a group in Charlotte.

After taking office Jan. 20, the Trump administration began highlighting what it has characterized as a new and more aggressive effort to target illegal immigration and deliver on a key campaign pledge to carry out mass deportations. So far, the enforcement efforts have been primarily individual arrests, rather than sweeps of factories, farms or other large-scale sites. Immigration and Customs Enforcement has reported on social media more than 5,000 arrests in around a week’s time.

An estimated 14 million immigrants lacking permanent legal status live in the United States, according to demographers and other experts. The number includes people with no legal status as well as people who have some form of temporary status that is being contested in court or has been threatened with termination by the Trump administration.

Arresting and deporting even a small share of the population with no status or contested status is all but impossible. But stirring anxiety and uncertainty among those millions of people appears to be far easier, stoked by sharp rhetoric from Trump and his top aides and fed by news footage of federal agents massing in communities from Seattle to New York.

Even schools, churches and hospitals, places long considered insulated from immigration enforcement, have become fair game after the Department of Homeland Security’s recent announcement that such locations were not off limits to agents.

Thomas D. Homan, Trump’s border czar, said that allowing immigration agents to have access to sensitive sites gave them the ability to pursue targets wherever they want, in line with other law enforcement agencies.

“It’s not like we’re walking in and arresting everybody in the building, so the institution shouldn’t be afraid. The criminal alien should be afraid,” Homan said.

In San Francisco, Karen Rodriguez rushed to pick up her 7-year-old son from school after parents were notified by a worker there that ICE agents had been spotted in the area.

“Fear is definitely a feeling we all have,” said Rodriguez, 30, of Colombia. She said that she, her husband and their son had crossed the border and were planning to apply for asylum.

Most immigrants without legal permission have been in the country at least a decade. They work in large numbers in construction, agriculture and other sectors, and they often have children who were born in the United States. Many have felt that if they stayed out of trouble with police, they would be relatively safe here.

No more.

Even in Los Angeles and San Francisco, cities that have passed laws to protect their immigrant communities, people are altering their routines.

At the Park Plaza Barber Shop in Los Angeles, there was only one customer at 5:15 p.m. last Tuesday. Ordinarily, most or all 10 chairs would be occupied, with more patrons waiting, said the owner, José Anguino. But in a neighborhood flush with immigrants, many were lying low, he said.

“Everyone is terrified, and they don’t want to spend money because they don’t know what could be coming,” said Anguino, who has owned the business for three decades.

Across the country, in Charlotte, Apolo Santos, the pastor of an Assembly of God Church, which ministers to the area’s fast-growing Brazilian community, said that his congregants were scared when President Donald Trump was last in office, “but not with this intensity.”

“People think ICE is everywhere,” he said, which is hurting church attendance.

Garcia, of Embrace All Latino Voices, the advocacy group, said that some people were starting to talk about returning to their home countries.

Self-deportation, or the idea that immigrants will just leave, has been promoted by proponents of highly restrictive immigration policies to achieve attrition through enforcement.

John Sandweg, a senior Homeland Security official in the Obama administration, said the strategy was clear. “The administration is creating a climate of fear as part of a self-deportation plan,” he said.

Details about the arrests have been limited, making it difficult to assess the extent to which the recent operations have been more expansive than the day-to-day enforcement efforts by ICE.

The specter of federal agents and the spigot of rumors on social media have created anxiety that can be hard to allay. The erroneous report by a middle school student in San Francisco of seeing an ICE agent on a public bus took on a life of its own.

A screenshot of a text message sent by a social worker at the school to colleagues said ICE agents “were in a black car, had dogs and entered the 29 bus. They introduced themselves as ICE. Then, they questioned passengers and detained several adults and school-age children.”

An Instagram post by a popular local photographer included a similar account that was shared more than 9,000 times. The school district sent an email to families warning them that agents might be in the vicinity of the bus route.

But there was no ICE action on any bus that day, according to the city’s police chief, William Scott, who said he had confirmed that with Homeland Security. He said the student most likely saw police officers board the same bus to look for a lost child and mistook them for ICE agents.

Lorena Melgarejo, who takes calls on a hotline for Faith in Action Bay Area, a social justice group in Northern California, said that there have been “ghost sightings” of ICE agents everywhere.

She has been telling people to call immediately if they witness a raid firsthand, but otherwise to double-check first. Her advice is that people remain vigilant while keeping up their routines — attending doctor’s appointments, sending children to school and showing up for work.

“We cannot be frozen by fear already,” she said.