An airline HK Express has apologized after two blind passengers say they felt “insulted and embarrassed" for being kicked out of the flight citing safety concerns.

Passengers Andy Chui, 34, and John Li, 27, were booked for an afternoon flight from Hong Kong to Tokyo on May 22, and said they had informed the airline about their disability, according to a statement from the Hong Kong Blind Union.

Li and Chui said they went through check-in without any issues and were escorted to the boarding gate as usual. On board, crew members briefed them about in-flight safety procedures but later removed them from the plane over safety concerns after learning they were traveling unaccompanied, according to Li and Chui.

“We felt insulted and embarrassed. They were treating us as if we were criminals,” Chui said in a press conference.

Blind Union president Billy Wong, said the handling of the situation left the passengers confounded because they had been able to travel alone without issues on other airlines.

Wong also called on the airline to investigate its protocols and treatment of travelers with disabilities, saying guidelines from aviation authorities were toothless.

“They need to ensure that companies comply with these guidelines and that there are punitive measures when companies discriminate against people with disabilities,” Wong told CNN.

HK Express said in a statement that “due to differing judgments made by the ground staff and aircrew,” the case was escalated to management for assessment and the “additional time required” to decide had led to the pair being “unable to travel on the original flight.”

HK Express said its staff had followed the airline’s “standard safety procedures,” during the incident, without specifying whether the two passengers had failed to comply with its protocols.

The airline added it was later confirmed that “the two passengers could travel safely without a companion,” and they were “re-accommodated on a later flight of their choice on the same day to their destination.”

“The decision made by the aircrew was entirely based on safety considerations, and the on-duty staff accompanied the two passengers as they left the cabin,” HK Express commercial director KK Ong said in a separate statement. “We sincerely apologize for the delay and inconvenience caused to the two passengers.”