LAKE ZURICH, Ill. (AP) — At least three dozen high school students in northern Illinois have tested positive for the COVID-19 virus after some attending summer sports camps showed symptoms of the disease.

Lake County health officials say investigations and contact tracing of the infections are tied to the camps held last week at Lake Zurich High School and multiple prior social gatherings.

Health officials said health screenings were conducted at the start of the camps on July 6 and some students who showed symptoms were turned away.

But other students experienced symptoms during the camps and were sent home. Health and school district officials met the next day and decided to close the camps.