McDonald's (MCD) shares sank nearly 10% in after-hours trading on Tuesday after the Centers for Disease Control and Prevention said the company's quarter pounder burgers had been linked to an E. coli outbreak in some states, with most illnesses in Colorado and Nebraska.

"This is a fast-moving outbreak investigation," the CDC wrote on its website. "Most sick people are reporting eating Quarter Pounder hamburgers from McDonald’s and investigators are working quickly to confirm which food ingredient is contaminated."

The CDC said McDonald’s has stopped using fresh slivered onions and quarter-pound beef patties in certain states while a source of the illness is confirmed.

One person has died from the outbreak, the agency said, and 10 hospitalizations have been reported across 10 states. McDonald's did not immediately respond to Yahoo Finance's request for comment.

Fellow fast-food giant Chipotle (CMG) went through its own E. coli outbreak in 2015, along with an outbreak of the norovirus. The company was forced to temporarily close 43 locations in Washington and Oregon as a result.

The CDC declared the outbreak over in February 2016, with the company undergoing an aggressive revamp of its food preparation methods.

But it took years for the Mexican fast-food giant to rebuild brand trust and recover its stock price as a result of the crisis. Shares are up more than 500% since 2016.

Alexandra Canal is a Senior Reporter at Yahoo Finance. Follow her on X @allie_canal, LinkedIn, and email her at [email protected].

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