Public health officials believe contaminated food caused a norovirus outbreak among dozens of people who attended an annual kids’ festival in Wisconsin, but they’re still investigating.

More than 60 people had symptoms of vomiting, diarrhea, low-grade fever and fatigue for multiple days, after attending the 19^th annual Special Kids Day festival at the North Wisconsin State Fairgrounds last month. The Wisconsin Department of Public and nine local health departments have been investigating.

“All evidence in the investigation suggests that the primary mode of transmission of norovirus was through contaminated food,” Jennifer Miller, spokeswoman for the state department, told the Leader-Telegram newspaper in Chippewa Falls, WI.

Event organizer Tom Luck told the Leader-Telegraph that 738 disabled students and about 1,000 people overall from 26 school districts attended the annual festival May 18-19.

“I really don’t know what happened,” Leuck told the newspaper. “I got a report that Monday (May 22) from a teacher that people were sick. I contacted the Chippewa County Health Department. I don’t have any answers of wher it came from. I don’t know. I’d like to know.”

Leuck said all food handlers at this year’s event wore gloves.