(CNN) Two brothers, their wives and children left war-torn Syria with 16 suitcases and crossed the border into Lebanon. They were finally on their way to the United States after working for almost 15 years to join their family members stateside.

But after a flight from Beirut to Doha, Qatar, and then to Philadelphia on Saturday, the two families were told to get on a flight back to Doha. It was because President Donald Trump had just signed an executive order denying citizens from seven countries, including Syria, entry into the United States.

Sarmad Assali and her daughter, Sarah, are among the relatives who were waiting to welcome the families to the United States. Sarmad Assali said they received a call from authorities Saturday morning telling them their relatives would not be allowed to enter the country.

The Assalis, US citizens who live in Allentown, Pennsylvania, weren't able to make contact with their family members until they were already headed back overseas. One of the brothers told Sarmad Assali they were not allowed to make calls or use the Internet while they were held.

According to the Assalis, their family members do not speak English very well and were told by authorities they could either be detained and have their visas taken away, or they could take the first flight back to Doha.

Frightened and facing a language barrier, the six family members chose the second option. Sarmad Assali told CNN she wished she had been able to speak with them, since she would have told them to stay until she could arrive with her attorney.

A long immigration journey

The Assalis are Orthodox Christians, a group that has faced extreme persecution in Syria.

Their relatives, whom Sarmad and Sarah Assali did not want to identify for their protection, began their immigration process in 2003. In late 2015 they were finally approved to enter the United States on an F-4 visa for brothers and sisters of US citizens.

The relatives finalized their paperwork, immigration interviews and medical examinations during a 10-day trip to Jordan in late December last year.

The Assalis have helped bring family members to the United States before. In 2013, they were able to bring in one relative, and last month they were able to bring the brothers' sister and her daughter.

The brothers waited to join them until after they could pack up their homes in Syria, Sarmad Assali said.

"We bought them a house, we furnished it for them, to help them start a new life," she told CNN.

But that plan is now on hold until the family can figure out a legal route forward. They have been in touch with their congressman, Republican Charlie Dent, as well as attorneys to figure out a plan.

Dent took a very vocal stance Sunday on behalf of the Assali family.

"I certainly agree that we can always improve our visa vetting and refugee vetting program, and I don't have any question about that," Dent said on CNN's "New Day Weekend."

"But I think it's wrong in the case that I was dealing with, with the family already in flight when the order was issued, and having no idea at the time of arrival they would be turned around."

Mayor 'sickened' by situation

Their attorney, Jonathan Grode, has an emergency conference Sunday with other attorneys about the new regulations, Sarmad Assali said.

"It makes me so sad that this great country is doing this to our Christians and to these people and to my family," Sarmad said.

Philadelphia Mayor Jim Kenney released a statement about the two families' plight.

"I am sickened by reports that federal officials, without knowledge or cooperation of PHL Airport staff, detained and then turned away two Syrian families," Kenney said in the statement.

"By several accounts, these families waited months to obtain the proper documentation so they could come to our country legally. And still, they were sent back to a war-torn nation that has used chemical warfare against its own people. The Trump administration very well may have just given these families a death sentence."

Said Sarah Assali, "We're all feeling a lot of anger, a lot of disappointment in our government. ... It's against our ethics as Americans."

At a protest in front of Philadelphia International Airport's international arrivals terminal Sunday surrounded by a massive crowd of chanting supporters waving pro-immigrant signs, Tawfik Assali, the son of two of the people turned away and nephew of Sarmad and cousin to Sarah, told CNN he had been very excited to see his parents.

"I was, like, one hour-and-a-half away from them," he said. "I haven't seen them for three years, so, it was really hard for me to not hug them, to not be with them."

While attorneys are still working on the case, he and Sarah both said they were encouraged and felt support from the large crowd that turned out Sunday and the other people who had reached out to help the family. Sarah also said that her family will begin a GoFundMe page to support her family members' travel expenses and legal fees.

"Thank you to everyone," Sarah told CNN. "We didn't expect this, we never thought we'd be in the position we're in now. So I'm very thankful. This is the America that we do know, and that we do love. And I'm just grateful."