Donald Trump’s executive order to close America’s borders to refugees and immigrants from some Muslim-majority countries caused chaos on Saturday, as people who had flown to the US were held at major airports while others were barred from boarding flights or were pulled off planes overseas.

By Saturday evening, there were 11 people in detention at New York City’s John F Kennedy airport who had arrived from Iraq and other barred countries, according to two Democratic members of Congress, Jerry Nadler and Nydia Velazquez, who joined protests at the airport.

According to representatives of immigration and civil rights group who spoke to reporters on a group call, other travellers were being held in Atlanta, Houston and Detroit.

Pre-approved refugees, students and workers holding visas and residency green cards were barred from flights to the US, according to reports emerging from Amsterdam, Frankfurt and Cairo and other cities across Europe, the Middle East and Africa.

As confusion reigned, a spokeswoman for the Department of Homeland Security confirmed to Reuters that people with green cards, making them legal permanent US residents, were included in the ban.

“It will bar green card holders,” wrote Gillian Christensen, acting DHS spokeswoman, in an email.

Trump’s executive order, signed on Friday in Washington, temporarily banned refugees from around the world, blocked Syrian refugees indefinitely and halted entry for people from seven predominantly Muslim countries: Iraq, Syria, Iran, Yemen, Sudan, Libya and Somalia.

A state department spokesman confirmed to the Guardian that travellers who have dual nationality between a country on the list and another non-US country, for instance UK-Iraqi or Canadian-Somali citizenship,are barred from entering the US for 90 days. The order provides for giving priority to religious minorities in those Muslim countries; Trump has said the US will in future prioritise Christian refugees.

In New York City, two Iraqi refugees were detained at JFK airport. One, Hameed Khalid Darweesh, had worked in Iraq for the US government for 10 years. The other, Haider Sameer Abdulkhaleq Alshawi, was coming to the US to join his wife who had worked for a US contractor.

Congressman Nadler told the Guardian that anyone who was detained at an airport should “not sign anything and ask for a lawyer”.

“Donald Trump should revoke the executive order,” he said. “It’s unconstitutional on the grounds of religious discrimination.”

The American Civil Liberties Union (ACLU) and other groups filed a lawsuit challenging the detention of the two Iraqi men, and Darweesh was allowed to enter the US on Saturday afternoon. He spoke before around 100 protesters outside terminal 4 at JFK airport, who shouted: “No hate, no war, refugees are welcome here.”

Darweesh told the Guardian he felt no ill will toward airport authorities. “They are good people,” he said. “They are just doing their duty.”

Becca Heller, executive director of the International Refugee Assistance Project (IRAP), said “dozens remain detained” around the US amid confusion between local authorities, federal agencies, attorneys and the White House. “Nobody knows at this point.”

Mark Doss, an attorney for IRAP, told the New York Times that a border agent directed him to the White House with his complaint: “Mr President, call Mr Trump.”

Thanu Yakupitiyage, a spokeswoman for the New York Immigration Coalition (NYIC), told the Guardian: “This is absolutely dehumanizing, I am livid, it’s outrageous. We are sending someone to JFK airport to speak to customs and border control about this, people are in a state of shock.”