Not a good way to start the school year: local health officials in McPherson, Kansas, are investigating a possible outbreak of foodborne illness linked to a back-to-school cookout last Sunday.

Fern Hess, director of the McPherson County Health Department, said St. Joseph Catholic School in McPherson delayed its planned first day of school on Wednesday because of a “significant number of students and staff who were ill.”

The school opened Thursday instead.

Hess said that based on symptoms and the time frame, health officials suspect the illnesses were caused by foodborne contamination from a Sunday, back-to-school barbecue.

The food served there was a combination of food provided by the school and food brought by people who attended.