A private school in south Fulton County was closed Friday while health officials investigated what caused dozens of students to fall ill.

The Fulton County Board of Health was called Wednesday when students at Landmark Christian School in Fairburn presented similar symptoms, including vomiting, nausea and diarrhea. The board was notified after school administrators contacted the Georgia Poison Center, health officials said.

Jason McMaster, Landmark Christian’s headmaster, told Channel 2 Action News there were a “higher than average rate of students” who reported feeling sick and showed signs of gastrointestinal issues.

The school is trying to account for all the students and staff who were exposed. There has been speculation that a student who traveled during the recent winter break may have been exposed to norovirus, he said, although health officials said Friday they have not completed their investigation.

“We take the safety of our students seriously,” McMaster said in a statement to Channel 2. “When we recognized that several students had fallen ill with similar symptoms, we acted quickly to seek advice and follow the advice of experts.”

Landmark Christian has been voluntarily closed since 11 p.m. Wednesday and is not scheduled to reopen until Monday. The school called in its vendors to perform a deep clean.

“Upon learning of the incident, we followed standard protocols which included a disease investigation by our epidemiologists and an environmental health assessment at the school,” health board officials said in a statement. “Additional information is being collected by our epidemiologists through patient interviews to determine the common exposure/source of the illness. Further steps will be taken based on the results.”

Landmark Christian was also closed Monday and Tuesday because of a massive water main break that left large swaths of the county with low water pressure.

RELATED: As water returns to south Fulton, frustration with response mounts

A boil water advisory was lifted for all affected customers at 8 a.m. Thursday.

McMaster said many classes have assigned students coursework electronically, but the school has also added three full instruction makeup days to the calendar.

The board of health plans to follow up with the school and the affected students when classes resume Monday.

Until then, health officials are recommending students and staff follow hand hygiene protocol and see a health care provider if illness is severe.

In other news:

Just before 11 p.m. Thursday night, the bill passed the House 93-73.