A federal judge blocked the deportation on Saturday of dozens of travelers and refugees from seven Muslim-majority nations, stranded at U.S. airports under an order from President Donald Trump, after a lawsuit filed on behalf of two Iraqis with ties to U.S. security forces.

In the lawsuit filed in federal court in Brooklyn, New York, the two men challenged Trump's directive on constitutional grounds. The suit said their connections to U.S. forces made them targets in their home country and that the pair had valid visas to enter the United States.

The lawsuit highlights some of the legal obstacles facing Trump's new administration as it tries to carry out the directive, which the president signed late on Friday to impose a four-month ban on refugees entering the United States and a 90-day hold on travelers from Syria, Iran and five other Muslim-majority countries.

In an emergency ruling on Saturday, U.S. District Judge Ann Donnelly ordered U.S. authorities to refrain from deporting previously approved refugees as well as "approved holders of valid immigrant and non-immigrant visas and other individuals ... legally authorized to enter the United States" from the countries targeted in Trump's order.

The American Civil Liberties Union, which sought the temporary stay, said it would help about 100 to 200 people who found themselves detained in transit or at U.S. airports after Trump signed the order.

"I am directing the government to stop removal if there is someone right now in danger of being removed," Donnelly said in the court hearing. "No one is to be removed in this class."

U.S. Department of Justice attorney Susan Riley during the hearing said, "This has unfolded with such speed that we haven't had an opportunity to address all the legal issues."

Many of the people in a huge crowd that had gathered outside the Brooklyn courthouse broke out into cheers after word of the judge's ruling filtered out.

The U.S. Department of Homeland Security in a statement hours later said only a small fraction of airline passengers arriving in the United States on Saturday were "inconvenienced while enhanced security measures were implemented."

"These individuals went through enhanced security screenings and are being processed for entry to the United States, consistent with our immigration laws and judicial orders," the statement said.

The department said Trump's executive order remained in place and that its officers would enforce it.

Separately, a group of state attorneys general were discussing whether to file their own court challenge against Trump's order, officials in three states told Reuters.