A view of the floor of the Republican National Convention at Quicken Loans Arena in Cleveland, July 18, 2016. (Doug Sovern/CBS)

CLEVELAND (KCBS) – Members of the California delegation at the Republican National Convention in Cleveland have fallen sick with the norovirus, a highly contagious stomach bug that causes diarrhea and vomiting.

KCBS reporter Doug Sovern first tweeted the news of the outbreak Tuesday.

About a dozen in CA delegation felled by norovirus now, moving them offsite as a precaution to keep from spreading. #RNCinCLE (I feel fine) — Doug Sovern (@SovernNation) July 19, 2016

Sovern said the outbreak started among some members of the delegation on Sunday and spread to more than a dozen members.

Infected members have been moved offsite to stop the spread of the virus. An email sent to members of the California delegation urges them not to share food or to shake hands.

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Republican delegations from other states have not reported any norovirus infections.

The highly contagious virus is usually spread through contaminated food or water, but the source of this outbreak is unclear.

According to the Centers for Disease Control and Prevention, a person usually develops symptoms between 12 to 48 hours following exposure. Most people feel better between one to three days.