The U.S. Center for Disease Control and Prevention (CDC) warned Tuesday of a “fast-moving” E. coli outbreak stemming from McDonald’s famed quarter pounders.

In the center’s ongoing investigation opened Tuesday, 49 cases, 10 hospitalizations, and one death have been documented across 10 states. The states include Oregon, Utah, Montana, Wyoming, Colorado, Nebraska, Kansas, Iowa, Missouri, and Wisconsin, although the CDC notes other states could be affected. Colorado has the highest number of infected individuals, totaling 26. One child has been hospitalized with complications from hemolytic uremic syndrome (HUS), affecting the kidneys, according to TODAY.

“Most people in this outbreak are reporting eating the Quarter Pounder hamburger at McDonald’s before becoming sick. It is not yet known which specific food ingredient is contaminated,” the CDC writes in their warning.

McDonalds, which has 14,000 restaurants across the U.S., responded to health officials saying they have temporarily stopped selling slivered onions and quarter pound beef patties in some states as the investigation continues.

McDonald’s USA President Joe Erlinger, in an appearance on the TODAY show Wednesday morning, says it’s safe to eat at the $225 billion-valued food chain and that he is not concerned about customers’ health.

“We are very confident that you can go to McDonald’s and enjoy our classics,” Erlinger said. “We took swift action yesterday to remove the Quarter Pounder from our menu.”

He adds: “This was swift and decisive action by us, and it is the quarter pounder and two ingredients on that quarter pounder that are under investigation by the CDC. So I want to say to our consumers that you can confidently go to McDonald’s today.”

Symptoms of E. coli include diarrhea, a fever over 102 degrees Fahrenheit, constant vomiting, stomach cramps, and dehydration, from dry mouth and throat and dizziness. It’s important to see a health provider if you feel sick. The onset of symptoms usually begin three to four days after consumption and typically reside after five to seven days. In severe cases, it can lead to kidney failure, particularly for younger children and older adults.

“We will be working with the CDC and cooperating with them on the investigation, and we’ll take in more data and let the science continue to lead our actions,” Erlinger said on the TODAY show.