A graduation party in the Sturgis area is suspected of being the source of foodborne illness last weekend that affected six people.

According to Steve Andriaachi, environmental health officer for Branch-Hillsdale-St. Joseph Community Health Agency, a member of the family with food service background catered the party. There has been no laboratory report completed yet regarding what caused the illness. Andriaachi said it is too early to release any details about the investigation.