LAKE ZURICH, Ill. (WGN) — Health officials are working to contain an outbreak of COVID-19 linked to a high school in the northern suburbs of Chicago.

Lake County health officials say 36 students at Lake Zurich High School have tested positive for the virus.

Officials said the cases may be traced to a number of social gatherings that took place before the school opened its summer athletic camps last week.

A mobile testing site was set up at the high school on Sunday and 355 people were tested. The 36 students who tested positive did not participate at the mobile site.

The health department tells WGN they are still awaiting the results from the mobile site, and are hoping to get them later this week. They say when the results do come back, it is likely the number of positive cases linked to the school will continue to rise.

The testing site was prompted after many student athletes were turned away from an athletic camp after failing temperature checks and health screenings last Monday.

By Tuesday, the school suspended the camps until further notice.

Officials have recommended that all 371 student athletes and their coaches self-quarantine for 14 days.

Due to this outbreak, Lake County will host another free mobile testing site in the parking lot of Lake Zurich High School’s Performing Arts Center on Sunday, July 19 from 9 a.m. to 5 p.m. — or until all 500 tests are exhausted. Lake Zurich High School students and staff are priority and will need to provide identification.

General public testing will start at 11 a.m. on Sunday.