The Centers for Disease Control and Prevention (CDC) issued a food safety alert on Tuesday which said an E. coli outbreak linked to McDonald’s burgers has led to one death and ten hospitalizations. “Most people in this outbreak are reporting eating the Quarter Pounder hamburger at McDonald’s before becoming sick,” the alert read.

The Centers for Disease Control and Prevention and other federal agencies are investigating an E. coli outbreak linked to McDonald’s Quarter Pounders, sending McDonald’s stock down 7% in after-hours trading.

Ten people have been hospitalized and one older person in Colorado has died after E. coli infections linked to McDonald's Quarter Pounder hamburger in 10 states, the U.S. Centers for Disease Control said on Tuesday.