At least nine people were taken to the hospital Monday night from O'Hare International Airport after they became violently ill in the international terminal.
Chicago Fire Department officials said the people were part of a tour group of about 50 that had been on a bus trip through the Midwest. They came to O'Hare to board a Scandinavian airline to Copenhagen, when some people began throwing up around 11 p.m. in the terminal.
Each of the nine sickened passengers was taken by ambulance to area hospitals. They were described as being in good condition but very sick with symptoms of vomiting and upset stomachs.
The remaining tour group members were allowed on the plane, but once on board, another person started getting sick, fire officials said. The captain then stopped the flight and decided to let everyone from the tour group off the plane.
Some went to the hospital and others received vouchers for area hotels.
It's not clear what caused the illness.