Immigration advocates reacted with sadness and anger Saturday to news that an Irish immigrant who was chairman of the Gaelic Athletic Association in Boston was deported last week despite having no criminal record.

“It just throws a big shadow over people’s dreams, this being the land of opportunity,’’ said Ronnie Millar, executive director at the Irish International Immigrant Center. “It creates a tremendous uncertainty about the future. People are really afraid.’’

John Cunningham, a 38-year-old electrical contractor, had lived in America for 18 years. But he arrived here on a 90-day visa, and Immigration and Customs Enforcement officials arrested him at his Brighton home on June 16 and held him until his deportation. His visa violation, they told the Associated Press, made him an “enforcement priority.’’ He was returned to Ireland on Wednesday, according to the Associated Press.

‘‘His significant overstay was cause and reason enough,’’ ICE spokesman Khaalid Walls told the Associated Press last week. ‘‘Someone who overstays a visitor visa is flagrantly violating the granted benefit.’’

President Trump signed an executive order in January that stepped up immigration enforcement, scrapping old guidelines that placed the priority for removal on undocumented immigrants who have criminal records or pose a threat to the community.

“The ICE director said that anyone who is undocumented ought to be looking over their shoulders,’’ said Millar, referring to remarks that ICE Director Thomas Homan made at a hearing on Capitol Hill in June. “It’s just a very sad situation we have at the moment. It’s not a very healthy way to be as a society.’’

And advocates say immigrants are living in fear. Millar said people come to the welcome center and ask about their future.

Eva Millona, executive director at the Massachusetts Immigrant and Refugee Advocacy Coalition, said people have been asking if they should leave, or close their businesses and bank accounts.

Just the other day, she said, she was talking to a mother from Syria, whose family is seeking asylum in the United States. The woman’s son is so stressed, she said, that he begged not to be made to go to school. He thought the family would be deported back to Syria and killed.

“Under the Obama administration, at least there was a priority list of people being deported,’’ said Millona. “Under the current administration, no one is safe, regardless of the fact that they are part of the commuinty, they work, they have no convictions whatsoever.’’

Families in which some members are here legally and others are undocumented, she said, are particularly afraid — because deportation not only means the danger of returning to countries people fled, but also the destruction of their families.

“It’s really a desperate situation,’’ said Millona.

Material from the Associated Press was used in this report. Evan Allen can be reached at evan.allen@globe.com. Follow her on Twitter @evanmallen.