Senators Elizabeth Warren of Massachusetts and Cory Booker of New Jersey and New York Representative Jerry Nadler were among the Democrats who attended protests Saturday against President Donald Trump's executive order on immigration.

The president's order, signed Friday, targets the Muslim community by barring Syrian refugees from entering the United States indefinitely and blocking citizens from seven predominantly Muslim nations for 90 days. Those countries are Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen. The order also blocks entry of all refugees to the United States for 120 days.

As stories of people being detained at airports around the nation surfaced, spontaneous protests against Trump's order sprung up, mostly at airports.

Warren attended such a protest at Boston's Logan International Airport.

“We have all heard about this order that President Trump has given. It is illegal. It is unconstitutional. It will be overturned,” Warren told the crowd. “An attack on anyone for their religious beliefs is an attack on the very foundation of democracy.”

Booker spoke at Washington Dulles International Airport.

“We must stand as witness,” Booker said. “We stand as resistors. We must stand in opposition to what others are trying to do to violate the law, the constitution, and our values.”

Nadler successfully intervened in at least one case out of New York City's John F. Kennedy Airport, where security held Hameed Khalid Darweesh and his family for 19 hours. Darweesh, who worked as a translator for American troops in Iraq, was granted a special immigrant visa.

“These are people who helped our military,” Nadler told PEOPLE. “They certainly are not dangerous.”

A federal judge on Saturday issued a partial halt to Trump's order, but did not rule on its constitutionality.

(Related: Trump's immigration order blocked as officials begin detaining refugees.)