Health officials say six people have died and at least 100 others have been sickened by pickles contaminated with E. coli bacteria in northern Japan.

The officials in Hokkaido said Saturday that the pickled Chinese cabbage was made by two local producers and sold across the prefecture. The first reports of illness occurred about 10 days ago.

Most victims were elderly people in nursing homes, but a 4-year-old girl in Sapporo city died last week a few days after eating the pickles.

Pickled Chinese cabbage is a popular Japanese side dish, and the deaths have shocked the country. Most food poisoning cases in the past have involved meat or seafood.

Officials are still investigating, but suspect insufficient sterilization may have been the cause.