The USDA is now disclosing the names of some of the retail stores that may have gotten contaminated hamburger.

Nearly 2 million pounds of ground beef were recalled by Wolverine Packing Co. in Detroit on Monday after 11 people in four states fell sick.

Click here for information on the codes.

According to the US Department of Agriculture, the contaminated meat may have been shipped to 10 states: Florida, Illinois, Indiana, Kentucky, Michigan, Ohio, Pennsylvania, Tennessee, Wisconsin and North Dakota.

Click here for the list of stores that may have gotten the meat.

The meat may have been sold in stores from the end of March to the start of May so the contaminated beef is most likely not in stores right now after the voluntary recall. The worry now: It may be in people's freezers.

Freezers do no kill E.coli. Heat kills the bacteria so follow these tips when grilling this Memorial Day:

1. If you see pink inside a burger this weekend, put it back on the grill.

2. Use a meat thermometer to make sure your burger is cooked all the way through. Cook it to an internal temperature of 160 degrees F., at which E.coli will die.

The Associated Press contributed to this story.