Two Muslim men from Dallas say their American Airlines flight was canceled because the flight crew did not feel comfortable flying with them on board, The Dallas Morning News reports. Abderraoof Alkhawaldeh and Issam Abdallah were both traveling on Sept. 14 to a charity meeting in Birmingham, Alabama, but were sitting on different sections of the plane. The men said they waved to one another during the boarding process, and Abdallah noticed a flight attendant standing very close to the restroom door as he was using it before takeoff. Passengers were then notified that the flight was canceled due to security reasons, and the plane had to be de-boarded.

After they got off the plane, the two men say they were trailed by law enforcement officers, were interviewed by an FBI agent, and had their bags searched a second time by TSA officials. Law enforcement allegedly told the men that Abdallah flushing the plane’s toilet twice raised suspicion. The men have filed a complaint with the U.S. Department of Transportation against the airline. “It was the most humiliating day of my life,” Abdallah said.

American Airlines said the flight was operated by regional carrier Mesa Airlines, and said the flight was canceled due to “concerns raised by a crew member and a passenger.” An American spokeswoman said the airline reached out to both men to “better understand their experience.”