Updated 12/16/14 – 5:39 p.m.

CHICAGO (CBS) — Hundreds of students in west suburban Oak Park were absent from school on Monday, after the district was hit hard by the flu.

A total of 563 students missed school Monday in Oak Park Elementary School District 97 – or nearly 10 percent of the district’s entire school body – most of them with flu-like symptoms. On Tuesday, more than 680 students were home from school.

“A lot of them were calling in with flu-like symptoms, but we have had some cases of strep throat, we have had some cases of upper respiratory issues, some of the common cold; so it seems to be a combination,” District 97 spokesman Chris Jasculca said.

It was the worst absentee rate for the district in five years.

On top of that, a couple dozen teachers and staff also called in sick.

School administrators said custodial workers spent Monday night disinfecting surfaces in the eight elementary schools and two middle schools in the District.

“It was extensive cleaning,” Jasculca said.

All the schools were open Tuesday, but school officials advised parents to keep their kids at home if they are sick. Children should be symptom-free for 24 hours before returning to school.

Ophelia Puccinelli, the daughter of CBS 2’s Mike Puccinelli, just got over the flu. She missed a few days of school at Percy Julian Middle School as a result.

“A lot of my friends aren’t at school,” she said. “A lot of people still come to school when they’re sick, and so it’s a really bad idea

Shawn Taylor, who has an 8th grader at Percy Julian, said “we’re real germophobes at my house.”

“My son is a maniac about washing his hands. So am I. We Lysol down,” she said.

Bob Miller said he didn’t bring his 8th grade son back to school until he was symptom-free.

“He’s been sick all week, and today’s his first day back,” Miller said.

The district said schools will be open on Wednesday.