Following E. coli outbreaks in Michigan and Ohio linked to ground beef from the Kroger Food Store, the US’s largest grocery chain announced on Wednesday it is voluntarily recalling all ground beef products that were sold between May 21 and June 8 at its stores.

There have been at least 32 cases of E. coli infections in Michigan and Ohio since the beginning of this month. Tests revealed that all the cases were caused by the same strain of the virus, 0157:H7.

The recall comes after the U.S. Centers for Disease Control and Prevention said Tuesday that outbreaks of E. coli infections in Michigan and Ohio were linked, and officials in both states suspected that ground beef caused the outbreak.

Meghan Glynn, representative for Kroger said they “are working with state and federal investigators to identify the supplier” that delivered them the infected ground beef Reuters reported.

Meanwhile, Kroger’s officials urge consumers to check their refrigerators and freezers and discard or return the ground beef products for a refund. Also, people are recommended use a digital thermometer to make sure the meat is cooked to at least 160 degrees Fahrenheit.

E. coli is a potentially deadly bacterium that can cause diarrhea, stomach cramps, vomiting and in most severe cases kidney failure. Most of the infected persons get well in 15 days. People predisposed to the infection include children, seniors, and persons whose immune system is weakened.

The CDC estimates that there may be about 70,000 infections with E. coli annually in the United States, with many of these cases not seeking medical care.

When dealing with E. coli outbreaks, people are urged to not eat ground beef that’s still pink in the middle, to drink water from safe sources, to not swallow lake or pool water while swimming, to keep kitchen utensils clean and to make sure restaurants cook the meat properly in case of dining out.