Federal immigration agents alarmed immigrant populations, community advocates and top politicians in Howard County after alerting local police Wednesday that they would conduct “criminal enforcement” in Columbia.

The warning, at a time of heightened tension across the United States as President Donald Trump has pledged to increase deportations, was followed up by sightings of U.S. Immigration and Customs Enforcement agents making arrests in Long Reach, which has a large Hispanic population, according to community members — further stoking fears.

“It was crazy this morning,” said Jimmy Johnson, a county resident who said he observed men in black ICE shirts in the parking lot of the Long Reach Village Center. “They were stopping people for no reason.”

The exact nature of the ICE actions was unclear — in part because the agency refused to confirm details of its operations in Columbia without names and dates of birth of individuals who may have been arrested.

By Wednesday afternoon, County Executive Calvin Ball had issued a statement saying that the activity was a “standard criminal enforcement operation, not a raid or sweep,” and stressing that Howard County police “were not involved in the operation in any way” and “will not assist ICE in the enforcement of civil violations of federal immigration law.”

“Though I want to put a stop to any misinformation, I also want to reassure every resident that Howard County opposes the criminalization of undocumented people, and our priority continues to be the safety and security of everyone in our community,” Ball said.

County police confirmed that they had been notified by ICE on Wednesday morning that the agency would be deploying in Columbia.

“This was a courtesy call to advise our personnel that there may be some activity,” said Sherry Llewellyn, a police spokeswoman. “ICE did not request HCPD assistance, nor did we offer. Howard County police are not involved in the operation in any way.”

Like Ball, Llewellyn described the nature of ICE’s activity in Columbia as “criminal enforcement.”

President Trump, who has railed against what he sees as uncontrolled immigration and vocally supported ICE, announced in a Tweet last week that the agency would be arresting and deporting “millions” of immigrants who have entered the country illegally.

After details leaked that raids were planned for Sunday, Trump on Saturday announced that any action would be postponed while members of Congress developed an immigration plan. In a tweet that day, he said: “The people that Ice will apprehend have already been ordered to be deported. This means that they have run from the law and run from the courts. These are people that are supposed to go back to their home country. They broke the law by coming into the country, & now by staying.”

Robert Andelman, who owns Nightmare Graphics in Columbia, said he was informed by employees Wednesday morning that an ICE raid took place in Long Reach and agents took a relative of one employee.

“My employees all came in at different times as normal,” he said. “They informed me that raids were happening in Columbia, Long Reach specifically, and one of my employee’s nephews was taken.”

Johnson, who lives in Long Reach, said he had stopped by the Exxon gas station off Tamar Drive to get his morning coffee before work when he saw several cars in the parking lot of the Long Reach Village Center. The 69-year-old, who works in masonry, said the gas station is frequented by construction workers and Latino workers who like him stop to get coffee before they head out to their daily gigs.

On Wednesday, he said he saw what appeared to be ICE agents, in unmarked cars and wearing ICE T-shirts, stopping people. He said he saw them ask people in a pickup truck for their IDs, and that two people in the truck were then let go while others in the truck were arrested. Johnson said he saw about eight or nine men get arrested.

Another man named Alex, who declined to give his last name because he is undocumented, said he was pumping gas at the Exxon station around 5:45 a.m. when he saw immigration agents in Toyota pickups detain two workers who were in what appeared to be a paint truck.

“I saw that they got them out … asked for their documents, then put them in their vans,” he said. “Then they quickly left.”

Elizabeth Alex, organizing director of the immigrant rights organization CASA, said such tactics are “really designed to stoke fear in immigrant communities” and often violate people’s rights.

“Most times when ICE is going out and knocking on doors, they don’t have a warrant for people, they don’t have a ton of information on people, they’re just fishing,” she said.

Baltimore was reportedly one of 10 cities slated for a surge in ICE raids before the president opted instead to give Democrats two weeks to negotiate a comprehensive immigration policy.

CASA has been holding “Know Your Rights” seminars in the Baltimore region in recent days in part because of that — telling people they have the right to remain silent and the right to an attorney.

People who are in their homes also do not have to open their door to ICE agents unless they have and can show a signed warrant, Alex said — something she hopes immigrant families remember when ICE agents are in their neighborhoods.

“They have rights, and they should remember what those rights are. Be prepared. Be organized. Know who your neighbors are and look out for those neighbors,” she said.

“Be careful and be safe, but don’t feed into the panic because that is exactly what ICE is trying to cause.”

In his statement Wednesday, Ball said he joined other elected officials in the region last week “to speak out on behalf of our immigrant communities and on the importance of safeguarding our civil rights.” He said he continues to “stand firm in those beliefs” and that the county believes “diversity is our strength.”

“To all residents of Howard County, undocumented or documented, I assure you that your County government will keep working to put your public safety first,” he said. “Our community will not be baited by fear and we must hold tight to our shared value of compassion. Howard County stands united against hate and in solidarity with one another.”

Jack Kavanagh, director of the county corrections department, said that while the county has an agreement to hold certain ICE detainees — including convicted felons and other individuals who have been charged with crimes and processed by ICE — it generally does not receive detainees the same day they have been arrested. He said he did not believe the county had any detainees as of Wednesday afternoon who had been arrested Wednesday in the county by ICE.

“When ICE arrests somebody, they don’t bring them here. We get them after they process them,” Kavanagh said. “We probably got some transfers out of state or federal prisons today, because we get them every day, but we don’t get direct arrests.”

Becca Niburg, an immigration lawyer who spent nearly a decade working as an immigration officer in the federal government, said that, based on the nature of the ICE activity in Columbia, she suspected ICE had “a particular person or people that they were specifically looking for,” though they “may have broadened their scope from there.”

And if that were the case, and agents didn’t find their targets Wednesday, more enforcement activity in the county is likely, Niburg said — particularly if the missing targets are considered high-priority violent criminals, gang members or drug traffickers.

ICE has provided no information indicating that the targets of their enforcement matched any of those criteria.

Baltimore Sun reporters Jessica Anderson, Erin B. Logan and McKenna Oxenden contributed to this article.