"During the flight, the cabin crew noticed that several passengers appeared ill," spokeswoman Julie King said in a statement.

Those who became ill are believed to be part of a group of more than 80 tourists who went on a river cruise in Asia and whose final destination is Montreal, Continental said in a statement.

The Centers for Disease Control and Prevention was called in and allowed the passengers to disembark. A CDC spokesman said the agency was investigating but suspected that seasonal flu was to blame.

The flight, Continental Flight 98, left Hong Kong on Monday with 272 passengers on board.