Local media is reporting that dozens of people became ill during a computer science conference at McGill University in Montreal, Canada, this past week.

The Montreal public health department is investigating the situation, according to the Montreal Gazette.

“I can confirm that our department has started an investigation, after we received a report about the incidents this morning,” spokesman Jean-Nicolas Aubé told the Gazette on June 13. 

He said Montreal’s food inspection agency is also looking into the incident. No further details were available because the investigation had just begun.

La Presse reported that numerous people spoke of suffering from severe diarrhea, vomiting and fever during the conference, as well as in the days following the event. Close to 700 people travelled to the university to take part in the information technology conference organized by Info-Can that ran from June 5 to 9.

“It felt like a gastro, like food poisoning. It was very widespread,” said David Meger, assistant professor at the school of computer science at McGill. Some members told organizers they had to go to the emergency department for treatment.

Participants and organizers say they think boxed lunches of beef and turkey sandwiches that were reportedly served at room temperature are to blame. Meger said the firm responsible for providing the food said it was certain it was not to blame.