Gastrointestinal illness sickened more than 130 cruise ship passengers aboard a Royal Caribbean cruise earlier this month. The cause of the outbreak has not been determined.

Over 140 passengers and crew members aboard a Royal Caribbean International cruise ship were sickened by a gastrointestinal illness that led to vomiting and diarrhea, according to the Centers for Disease Control and Prevention.

The US CDC has launched an investigation after passengers on the Royal Caribbean cruise started showing signs of acute gastroenteritis (AGE), which is usually caused by norovirus