A United Airlines flight from Vancouver to Houston was met by emergency responders from the Houston Fire Department on arrival as more than two dozen passengers suffered flu-like symptoms including nausea and vomiting.  The plane was later withdrawn for deep cleaning as a “precautionary measure.”.

In a statement United confirmed that “several passengers who had been on the same cruise and did not feel well were on United Flight 1528.”

The airline said it was “actively coordinating with health authorities to address the situation.”

United Airlines confirmed the incident, saying that various flyers from the cruise were ill and were aboard the same flight. It is not clear what caused the sudden symptoms in the passengers.

According to the airline, 163 passengers and six crew members had been on the flight, which took off from Vancouver.

It has not been confirmed which cruise ship the passengers came from.

Cruise Hive reported that only one was docked in Vancouver on Friday — Royal Caribbean International’s Radiance of the Seas . The vessel experienced a norovirus outbreak in April.

Business Insider reported that Royal Caribbean did not immediately respond to a request for comment as to whether Radiance of the Seas had experienced any cases of illness.

Three passengers were examined by first responders, but none needed medical assistance.