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.

READ MORE: UC Researchers Find North Coast Kelp Forest Nearly Wiped Out

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

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

READ MORE: Man, Woman Found Stabbed in Downtown Mountain View Sunday Morning

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.

California Delegation Helps Quell Floor Fight
Melania Trump Accused Of Plagiarizing Michelle Obama’s Speech
Live RNC Blog From CBS Cleveland

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.

MORE NEWS: Illegal Oakland Sideshow Takes Over Corner Near Police Headquarters

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.