MINNEAPOLIS (WCCO) — Five people in Minnesota have recently suffered an E. coli infection, which officials believe could be caused by a chopped salad kit.

The Center for Disease Control and Prevention announced Monday that it is investigating an outbreak of E. coli infections, which information indicates are linked to the Fresh Express Sunflower Crisp chopped salad kit.

As of Tuesday, a total of nine people had been infected in this outbreak, including five from Minnesota, according to the Minnesota Department of health. Three of the cases were reported in Wisconsin, with one in North Dakota.

The Minnesota illnesses are reported to have started on dates ranging from Nov. 8 to Nov. 16. Three of those infected have been hospitalized, with one having suffered a type of kidney failure caused by the infection.

Investigators are looking to determine which ingredient in the salad kit caused the infections. While romaine lettuce is present in the salad, the CDC is unsure if the outbreak is related to recent infections linked to romaine grown in California.

The CDC recommends consumers, restaurants and retailers throw away the kits, even if some of it has been consumed and no illness was reported.