Nearly 200 seventh grade students at John Adams Middle School were potentially exposed to the gastrointestinal illness during a five-day science trip to Yosemite, according to school officials.
Several students showed signs of illness while still on the trip last week, the school stated.
School officials said they were working with the Los Angeles Department of Public Health to establish control measures in order to prevent the spread of the illness.
Health officials said they believed the illness originated in Yosemite and potentially exposed students from dozens of school districts.
Health and school officials expressed concern that the illness could spread to siblings attending other schools in the Santa Monica-Malibu Unified School District.
To help keep the illness from spreading, John Adams Middle School and any other schools where cases are learned of will be cleaned.
Health officials said symptoms of the norovirus include nausea, vomiting, diarrhea, and fever. They said symptoms typically begin within an hour to 48 hours after exposure.
If you or your children begin to show symptoms, you were urged to immediately call the department of public health at (888) 700-9995.