The Cook County Department of Public Health said students and teachers at New Trier Township High School in Winnetka reported vomiting, nausea and abdominal cramping, The Chicago Tribune said Friday.

Officials said they expect lab tests to show that the illnesses are being caused by norovirus -- known for sickening hundreds of cruise ship passengers in recent years.

"It's clearly a gastrointestinal virus that's likely to be norovirus," a health department spokesman told the newspaper. "It passes from person to person very easily."

The school is being disinfected and students were told not to come back to school until they've been symptom-free for 24 hours.