BOSTON—Thousands of protestors rallied Sunday in Boston’s Copley Square, outraged over Pres. Donald Trump’s order blocking immigrants from seven largely Muslim countries from entering the U.S.

Protests broke out in city centers and airports across the country. The one in Boston—an academic hub for institutions including Harvard University, Massachusetts Institute of Technology and Boston University—was among the largest.

After Trump issued the executive order on Friday, federal judges in Boston, New York City and several other locations issued temporary rulings during the weekend in attempt to curb it. But its enforcement status remained unclear in some areas.

Many of those caught up in the situation were students or academics in science and medicine. Among those directly affected during the first 24 hours:

Mazdak Pourabdollah Tootkaboni and Arghavan Louhghalam—both Iranians and engineering professors at the University of Massachusetts, Dartmouth—had been in Paris for a conference on sustainable engineering and were detained at Boston’s Logan Airport for four hours Saturday, according to The Boston Globe. A judge ruled that the executive order could not prevent the two, permanent residents for more than a decade, from coming home.

Samira Asgari, an Iranian traveling to Boston to begin working on a tuberculosis project at Harvard Medical School, was turned away at the Frankfurt airport although her documentation was valid, The Boston Globe reported.

Kaveh Daneshvar, an Iranian molecular geneticist finishing postdoctoral studies at Harvard Medical School and Massachusetts General Hospital, told Nature that he will have to turn down an invitation to speak at a conference in Canada next month out of fear that he will not be allowed to return home afterward.

Sunday’s protest in Boston followed a rally Saturday night at Logan Airport, where local politicians including Massachusetts’ senior senator, Elizabeth Warren, expressed support for immigrants from all parts of the world.

The direct effect on scientists—and the large scientific, medical and academic communities in Boston—drove many of the people who turned up at the rally on Sunday. Here is a sampling of photos and comments from protestors who said concerns about science were among their reasons for taking part:

Loren Sherman, Senior Computer Science and Media Studies major, Massachusetts Institute of Technology

Credit: Michael Kuchta

“People who are trapped in other countries will feel like all Americans are not against them [because of this rally].”

Alex Bloemendal, Computational Scientist, Broad Institute of Harvard and MIT

Credit: Michael Kuchta

“This is an affront to human decency. I’m a scientist and the grandson of Holocaust survivors. We [scientists] maybe play a special role as guardians of empirical truth. We don’t have a monopoly on that, but we carry that torch in a special way.”

Henna Tirmizi, Anesthesiologist in Boston, with her husband Usman Farooq and daughter Adeena, 3.

Credit: Michael Kuchta

“I’m here because America’s a country that was built on immigration. Banning people from a few countries is incredibly racist.”

Angela DePace, Associate Professor of Systems Biology, Harvard Medical School

Credit: Michael Kuchta

“Science has always been an international collaboration. We’re here to stand with our colleagues and neighbors. Scientists believe fundamentally in data, facts, rational discourse and changing your mind when you are proven wrong. That very mindset seems to be what’s at risk here… Scientists are galvanized in a way they have not been in a long time. We like to think of ourselves as apolitical, but I don’t believe that’s possible in good conscience right now.”

Judith Steen, Neurobiologist and Dementia Researcher at Boston Children’s Hospital and Harvard Medical School

Credit: Michael Kuchta

“Our work is fueled by a diversity of ideas. Without that, novel work cannot be done. [The United States] has been the number one country to do science because of our diversity.”

Bettina Hein, CEO of a Boston-based software company, German Immigrant

Credit: Michael Kuchta

“I’m here because I’m an immigrant. I’m one misdemeanor away from being deported. I create jobs for a living. I have almost 100 employees and one-third of my staff is foreign-born. It’s a very precarious situation. This makes me worried for the future of Western democracies.”

Noor Al-Alusi, master’s degree candidate and epidemiologist, Harvard School of Public Health

Credit: Michael Kuchta

“This is a violation of our rights. I’m just surprised that Trump would be able to do so much damage in so little time. It worries me as an epidemiologist, it worries me as a daughter of immigrants and it worries me as a Muslim.”

Ashok “AJ” Kumar, chief scientific officer for a Boston software company, native South Dakotan who moved to Boston to get his PHD at Harvard

Credit: Michael Kuchta

“I’m here both as a scientist and son of immigrants. I think it’s important that we have policy driven by facts and information rather than fear. My dad’s in the military and served in Iraq, where he had local translators [and others who helped]. For us to slam the doors on them is just immoral.”

Veronica Lane, Master’s Degree student in Robotics and Artificial Intelligence, MIT

Credit: Michael Kuchta

“It makes me really mad that Trump – a lot of people thought he wouldn’t do this. These people [from the banned countries] are great scientists… This has nothing to do with Christianity and what Jesus believed.”

Dr. Hosam Attaya, Interventional Radiologist, Massachusetts General Hospital

Credit: Michael Kuchta

“I am a Muslim and I believe in the power of touch. As a physician, this covers two birds with one stone.”