Bags of broccoli florets that were sold at Walmart stores in 20 states are affected by a Class I recall due to concerns over possible listeria contamination.

The U.S. Food and Drug Administration has labeled the broccoli recall as a Class I, the highest risk level issued by the agency.

A recall was issued for Marketside Fresh Broccoli Florets, a brand of 12-ounce washed and ready to eat broccoli florets sold at Walmart, in Louisiana and 19 other states.