An E. coli outbreak linked to McDonald’s Quarter Pounders has affected at least 75 people across 13 states, resulting in one death and 22 hospitalizations, the CDC reported.

Fresh onions from Taylor Farms in California, used on the burgers, are suspected as the source.

The CDC noted the actual number of cases may be higher.

McDonald’s has temporarily removed Quarter Pounders from menus in affected areas while working with suppliers to resolve the issue, NPR has reported.

Shares for McDonald’s fell by 2.7% following the news.

Written by B.C. Begley