Elementary school students returned to their campus in Buford on Monday after the building was sanitized to prevent the spread of stomach flu.

Public health department officials recommended closing the Harmony Elementary School campus on Friday after more than 20 percent of the school's nearly 640 students as well as eight teachers showed symptoms of the virus.

Officials with the East Metro Health District visited Harmony Elementary Friday to investigate the cause of the students' illness as Gwinnett Schools crews cleaned the building. Health officials suspected the outbreak was caused by gastroenteritis, but wanted confirmation.

Health officials have not concluded their investigation, but the number of children out sick dropped from 130 to 42 students.