A deadly E. Coli outbreak across 10 states has been linked to McDonald's Quarter-Pounders, CDC says

• McDonald's Quarter Pounders are making people sick with E. coli, the CDC said Tuesday.
• One person has died, and 10 others have been hospitalized after eating the hamburgers, the agency said.
• McDonald's shares plunged in extended training on Tuesday following the announcement.

McDonald's shares dropped more than 9% on Tuesday after the Centers for Disease Control and Prevention said one person died and ten others were hospitalized in connection with an E. coli outbreak linked to the fast food chain's Quarter Pounders.

The health agency said the "fast-moving" outbreak is primarily affecting people in Nebraska and Colorado. It added that most people affected reported eating a Quarter-Pound hamburger.

The fast food chain did not immediately respond to Business Insider's request for comment.

A total of 49 cases across 10 states have been reported so far, but the extent of the outbreak is "likely much higher," the CDC said

According to the CDC, McDonald's has pulled some ingredients from the burgers and paused Quarter-Pound sales in some states. Investigators are working to determine which ingredient is making people sick.

The company's shares plunged about 9% in extended training on Tuesday following the announcement.