Lawyers for immigrants sent back to their homelands after landing in Philadelphia last weekend on Tuesday sued President Trump and his administration, arguing that his executive order was unconstitutional and that they should be immediately allowed to return to the United States.

The lawyers say two Syrian brothers, their wives, their two children, and an Iranian woman traveling alone — each of whom had a valid visa — should be admitted without delay. They claim the travel ban Trump imposed violates the equal protection guarantee of due process as well as the First Amendment by preferring one religion over another.

"This effort over the weekend was part of a much bigger battle for immigrant rights and one that will continue for a long time," said Molly Tack-Hooper, staff attorney at the ACLU. "We tried to negotiate with the federal government to get their visas reinstated we were not able to do that."

Assigned to a judge in Allentown, the lawsuit filed Tuesday seeks a temporary restraining order barring the Trump administration from blocking the immigrants' return to the U.S. A second suit is expected later this week.

Besides the president, it names as defendants the Department of Homeland Security and its secretary, John Kelly; Customs and Border Protection and its acting commissioner, Kevin McAleenan; and Kevin Donohue, the port director of the Philadelphia field office of CBP.  Louis Lappen, the acting U.S. attorney in Philadelphia, said his office was reviewing the lawsuit but declined to comment further.

The filings mark the latest legal challenges to Trump's order, one that has sparked criticism, confusion, and demonstrations across the globe, including weekend protests at Philadelphia International Airport.  Similar legal challenges have been filed in Los Angeles, Boston, Virginia, New York, and Seattle.

The seven travelers to Philadelphia were barred early Saturday, just hours after Trump's order suspended admission of all refugees for 120 days; of migrants from seven predominantly Muslim countries for 90 days; and of Syrians indefinitely.

The lawsuits were unveiled at a news conference at Philadelphia City Hall, where relatives of the immigrants were flanked by lawyers, advocates, and city officials. Mayor Kenney lambasted the president's order, which he called an "unconscionable, cold and callous attitude about human beings."

"Imagine spending 15 hours on a plane after two years of being vetted to be turned around in Philadelphia, the birthplace of America," he said, "and put back on that same plane and be sent back 15 more hours to a  country whose own government is gassing and bombing its own citizens."

He was referring to the Allentown-area family that spend 14 years helping arrange their relatives' immigration, only to see them forced to return to Syria after landing in the U.S.

Ghassan Assali, an Allentown dentist, had been expecting to welcome his two brothers and their families to a home here he had prepared for them. Instead, Customs and Border Patrol agents called and said they had been put on an flight back to Damascus via Qatar.

"Every day that they are not here they are faced with a dangerous and unstable situation back in Syria,"  said Joseph Hohenstein, one of the lawyers in the case.

In an odd twist Tuesday evening, Sarmad Assali, Ghassan's wife, told NBC Nightly News that her family in Allentown had voted for Trump.

"I understand he wants to make America safe," she told the network. "We're all on with this. I definitely want to be in a safe place. But people need us, and we need to be there for them."

The Iranian woman who was turned away in Philadelphia, 68-year-old Fatemeh Sheikhi, left Iran aboard a Qatar Airlines flight about 13 hours before Trump signed the order, according to her family.

Her daughter was waiting for her in the terminal with flowers, but the two were not allowed to talk or see each other. An employee from Qatar Airlines took a package Sheikhi had for her two daughters -- gold necklaces meant as birthday presents -- to the arrival hall and brought back the flowers for Sheikhi to take with her on the long flight back.

"We are students here. We are working, studying, and contributing to the society," said the older daughter, Shadi Ahmadi Darani, 28, a Ph.D. student at Michigan Technological University. "What message are you sending out by preventing us from seeing our families? ... you're isolating the country from people who have no danger to the society. They just want to come here and build a life."

The sisters said they did not know whether they wanted to stay in the United States beyond school.

"Right now we don't know what's going to happen," Shadi Ahmadi Darani said. "We don't know. What's the next executive order going to be?"