More than a dozen American Airlines passengers were hospitalized after their Miami-to-Boston flight landed at Logan International Airport on Sunday. According to reports, a mysterious illness affected 13 flyers who were part of a student group returning from a trip.

The teenagers, aged 15 to 17, reported feeling sick and were taken to Massachusetts General Hospital after their flight landed. Local reports said the victims were complaining of stomach virus symptoms, and some of them were also vomiting on the flight. 

An American Airlines representative told the New York Post that the students visited the Galapagos Islands and Ecuador before passing through Miami. Other than the 13 students who were hospitalized, three other members also reported feeling ill. Boston EMS responded to the airport with multiple units after receiving a call, and later said the symptoms "were minor in nature.”

Since the plane arrived at the airport, emergency personnel cleared the airplane to fly again. No crew members or passengers outside of the student group reported symptoms. As of late Sunday, at least five patients were released from the hospital in good condition.

The airline later told Fox News that the students had dined at the same restaurant in Ecuador the night before of their flight to Boston. Officials were, however, unable to say for sure what caused the illness.