(CNN) California health officials are warning residents not to eat oysters from British Columbia, Canada, following a norovirus outbreak.

About 100 people got sick in California after they consumed the raw oysters, health officials said.

"As of April 27, approximately 100 individuals have reported illness after they consumed raw British Columbian oysters sold by restaurants and retailers throughout the state," the California Department of Public Health said.

"Laboratory testing has confirmed norovirus infection in several patients from both California and Canada. Although the number of reported new illnesses has decreased during the last week, the investigation is ongoing."

Canada has reported 172 cases of gastrointestinal illness linked to consumption of raw oysters.

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