The U.S. government said Tuesday it has closed its investigation into an E. coli outbreak tied to McDonald's Quarter Pounder hamburgers after determining there is no longer a safety risk.

The outbreak, which began in late October, sickened at least 104 people in 14 states, including 34 who were hospitalized, according to the U.S. Food and Drug Administration. One person in Colorado died and four people developed a potentially life-threatening kidney disease complication.

The FDA, which conducted the investigation along with the U.S. Centers for Disease Control and Prevention and state health departments, linked the outbreak to yellow onions distributed by California-based Taylor Farms and served raw on Quarter Pounders at McDonald's restaurants in Colorado, Kansas, Wyoming and other states. Taylor Farms initiated a voluntary recall of yellow onions on Oct. 22.

Federal and state health officials in Colorado didn't find the strain of E. coli that caused the illnesses in onions it tested or in any samples from the environment. But they concluded that evidence showed that recalled yellow onions were the likely source of the outbreak.

"McDonald's is no longer serving recalled onions and there does not appear to be a continued food safety concern related to this outbreak," the FDA said Tuesday in a statement.

McDonald's briefly pulled Quarter Pounders from one-fifth of its U.S. stores as a result of the outbreak. The company found an alternate supplier and resumed selling Quarter Pounders with slivered onions at all U.S. stores last month.

A spokesperson for McDonald's Canada has said the E. coli concern does not extend to the fast-food giant's Canadian locations.