A tomato recall due to risk of salmonella contamination has been designated as Class I, the U.S. Food and Drug Administration's highest warning level, the agency said. The FDA marked the tomato recall affecting three states as Class I, meaning there is a risk of "serious adverse health consequences or death," on May 28.

What was once a cautioned recall due to the possible presence of Salmonella in tomatoes sold in three states is now labeled as "deadly."

The Centers for Disease Control and Prevention has estimated that salmonella causes about 420 deaths annually in the U.S.