Detroit-based Wolverine Packing Co. is recalling about 1.8 million pounds of ground beef products believed to be contaminated with E. coli, the U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS) announced.

The ground beef was produced between March 31 and April 18 and was shipped to distributors for restaurant and retail use nationwide, FSIS said.

FSIS was notified of illnesses related to E. coli on May 12. Working with the Centers for Disease Control and Prevention (CDC), FSIS was able to trace the illnesses back to ground beef products prodced at Wolverine Packing Co.

Based on investigations, 11 people in four states have been affected. FSIS said it will continue to work with state and federal health officials on this investigation and will provide updated information as it becomes available.