The Japan Times reports that five of 21 people who fell ill after eating frozen cutlets sold by a company in Hiratsuka, Kanagawa Prefecture, have been found to suffer from food poisoning from the O157 strain of E. coli bacteria, prefectural health officials said Tuesday.

The patients’ symptoms included stomachaches and diarrhea. The O157 strain was detected from the cutlets and the patients’ stools.

The frozen cutlets, made of minced beef and pork, were sold by the meat company Niku No Ishikawa, according to the prefectural officials.

The best-before date of the products, made by a company in neighboring Shizuoka Prefecture on behalf of Niku No Ishikawa, was set at Feb. 26, 2017.

The cutlets were sold at 26 Ito-Yokado Co. supermarkets in Kanagawa and Chiba Prefecture. Ito-Yokado, a unit of Seven & I Holdings Co., had removed all of the products from its stores as of Wednesday.

The Kanagawa Prefectural Government is calling on purchasers of the cutlets not to eat them and contact the stores where they were bought.