The Minnesota Department of Health has identified more than 40 people who reported becoming ill after eating at the Greysolon Ballroom in Duluth, Minnesota, on Saturday and “we suspect there could be more,” said Doug Schultz of the department’s communications office.

About 250 people attended one event and 100 attended the other at the Greysolon, Schultz said. One was a wedding and the other a private party. The outbreak was first reported to the health department on Tuesday, he said.

The food was served by Greysolon Ballroom By Blackwoods and the business is cooperating with the investigation, he said.

As part of the investigation, investigators will check whether there are enough handwashing sinks at the establishment, if the refrigeration temperatures are adequate and whether any employees have been ill.