(LONG BEACH, Calif.) — California health officials have shut down an elementary school in Long Beach after at least 136 students and staff reported symptoms of norovirus as of Thursday, according to the city’s health department.

“Despite stringent control measures, there has been evidence of ongoing transmission and, as a result, the school will be temporarily closed until Wednesday so that deep cleaning — an outbreak management strategy — can be thoroughly conducted,” the Long Beach Health Department told ABC News.

Norovirus is a highly contagious virus that is the most common cause of viral gastroenteritis, which is an inflammation of the inside lining of the gastrointestinal tract, according to the Centers for Disease Control and Prevention. Although it’s often referred to as a “stomach bug” or “stomach flu,” norovirus illness is not related to influenza.

All school and child care operations at Carver Elementary will remain closed Friday through Tuesday, the district said. The school will not implement virtual classes while it is closed, but teachers are allowed to give students work to be completed at home.

A health screening process will be implemented when students return to school on Wednesday morning, according to the district.

“Health officials have determined that this length of closure is the most effective way to stop the further spread of this common virus,” the Long Beach Unified School District said in a letter to families.

“Norovirus is a very contagious virus that causes sudden vomiting, diarrhea, nausea, and abdominal pain. Norovirus spreads primarily through direct and indirect contact with an ill person’s feces (poop) or vomit,” the Long Beach Department of Health and Human Services said in a letter to families.

Direct and indirect contact can include changing diapers, caring for or sharing foods or utensils with a sick person, touching contaminated areas, surfaces or objects, and then touching their mouth or food before washing their hands, according to the health department.

Symptoms begin 12 to 48 hours after a person has come into contact with the virus and symptoms can last up to three days, health officials said.

Infected individuals are contagious as soon as they feel sick and can remain contagious up to two weeks. There is no specific treatment for norovirus, however, drinking fluids is important to replace fluids lost from vomiting and diarrhea, according to health officials.

On Wednesday, parents were told to notify the school of any students who continued experiencing symptoms of norovirus and to keep those students home, the district said.

Parents must also monitor students and staff must self-monitor every day before going to school.

“Students and staff with symptoms of norovirus must not go to school or work and must stay home until symptoms have resolved AND you stay symptom free for 48 hours (72 hours for cafeteria staff),” the department said.