Wolverine Packing Co. is recalling more than 167,000 pounds of ground beef shipped to restaurants due to possible E. coli contamination.

Fifteen cases have been reported in Minnesota, with illnesses starting from November 2 to November 10, the US Department of Agriculture Food Safety and Inspection Service said Wednesday.

Fresh products have a use by date of November 14. Frozen products are labeled with production date of October 22. Products have an establishment number EST. 2574B in the USDA mark of inspection.

Items were shipped to restaurants nationwide, the agency said, and it’s concerned that some products may be in restaurant refrigerators or freezers. All the products should be thrown away or returned and should not be eaten.

The Minnesota Department of Agriculture notified the Food Safety and Inspection Service on November 13 about illnesses in people who had eaten ground beef. On November 20, a ground beef sample collected by the Minnesota Department of Agriculture tested positive for E. coli O157.

People with E. coli infections may have symptoms including severe stomach cramps, diarrhea, fever and vomiting. Symptoms of infection usually begin three or four days after swallowing the bacteria. Although most people who become ill recover without treatment within a week, others can develop serious kidney problems and require hospitalization.

In a statement to CNN, Detroit-based Wolverine Packing said it was working closely with the Food Safety and Inspection Service and had notified all customers that received recalled products.

“We are also conducting an intensive internal audit to fully review suppliers and processes in place, including rigorous quality control measures, to maintain the highest standards of production,” the statement said. “As a third-generation, family-owned and operated company in business for nearly 90 years, we are committed to food and consumer safety. That is our highest priority.”