FILE - A sign outside a McDonald's restaurant, June 25, 2019, in Pittsburgh.

Several people were poisoned by E. coli for reasons linked to McDonald's quarter-pounder hamburgers. An elderly man died in Colorado and a child has been hospitalized for serious kidney complications.

An E. coli poisoning linked to McDonald's quarter-pound burgers has sickened at least 49 people in 10 U.S. states, including one who died and 10 who were hospitalized, health officials reported Tuesday.

An elderly man died in Colorado and a child has been hospitalized for serious kidney complications, the United States Centers for Disease Control and Prevention (CDC) reported.

The infections were reported between September 27 and October 11 in Colorado, Iowa, Kansas, Missouri, Montana, Nebraska, Oregon, Utah, Wisconsin and Wyoming. Colorado is the state with the highest number of cases with 26, followed by Nebraska with nine.

Everyone interviewed in connection with the outbreak had reported eating at McDonald's before getting sick, and most said they had eaten quarter-pounder burgers, the CDC said. The Department of Agriculture (USDA), the Food and Drug Administration (FDA) and state health authorities also launched investigations.

A specific ingredient has not yet been identified as the cause, but researchers are focusing on onions and meat. A preliminary investigation suggests that the possible source of contamination was the onions served in the hamburgers. The USDA tests the meat.

McDonald's released a statement indicating that preliminary findings suggest that some of the cases are linked to onions from a single supplier. The company has suspended distribution of those onions and temporarily removed quarter-pounder burgers from menus in affected states, as well as parts of Idaho, Nevada, New Mexico and Oklahoma.

“We take food safety as seriously as possible and this is the right thing to do,” the company said in the statement.