Health officials in York Region are investigating a possible norovirus outbreak at schools in the region, including one school where more than 100 students are reported to be home sick.

A large number of students at Thornhill Woods Public School reported flu-like symptoms this week. A spokesperson for York public health says tests are underway as to whether or not they've contracted norovirus.

York Region District School board won't confirm the exact number of students sick but one parent told CBC Toronto it's more than 100.

Parent Lee Lipes's daughter — who is in Grade 1 — was one of the Thornhill Woods students who fell ill.

"She had it for about 24 to 48 hours and then she was back in action so we're not too worried about it," he told CBC Toronto. "In my daughter's class I think about 80 percent of the kids weren't there."

Lipes said he heard that between 150 and 180 Thornhill Woods students have been sick. He said his daughter's symptoms were similar to the flu.

Schools scrubbed down

A note to parents from the principal at Thornhill Woods confirms that the school has seen a "high absentee rate" because of students falling ill with what appears to be a stomach bug.

Other schools in the region have confirmed cases of norovirus, but nothing that compares to the scale of the possible outbreak at Thornhill Woods, which has students from junior kindergarten to Grade 8.

Cases of norovirus have been confirmed at other schools in the region. Thornhill Woods was thoroughly cleaned and disinfected over the weekend.

Norovirus infection, which is characterized by nausea, vomiting, diarrhea and abdominal pain, can be easily spread.

Symptoms usually dissipate after 24 to 48 hours.

Students showing any symptoms are being asked to stay home.