CHICAGO (CBS) — Oak Park and River Forest High School is warning students to “stop engaging in risky behaviors,” such as hosting parties and ignoring mask requirements, after at least 24 students tested positive for COVID-19 so far this school year.

While the school has started the fall semester with entirely remote learning, Superintendent Dr. Joylynn Pruitt-Adams sent parents a letter announcing 24 current students have tested positive for the novel coronavirus since Aug. 15, three days before the semester began.

The superintendent said many of those cases can be traced to a large party.

“We have received information from both parents and students that a large indoor gathering of students recently was held at a local home, where mask-wearing and social-distancing were not observed. A significant number of positive cases are believed to have resulted from that event,” Pruitt-Adams wrote. “Students, I implore you: Please stop engaging in risky behaviors. They put not just you and your families but our entire community at risk.”

Illinois currently requires anyone over the age of 2 to wear a face covering in public. Health officials also have repeatedly urged people to help prevent the spread of COVID-19 by avoiding large social gatherings, staying at least six feet away from other people whenever possible, and staying home when they are sick. Anyone who tests positive for the virus, has close contact with someone else with a confirmed or probable case of COVID-19 should self-quarantine for at least 14 days, even if they don’t have any symptoms.

Pruitt-Adams urged people in the community to cooperate with the school’s contact tracing efforts.

“I understand that sharing information about unsafe behavior may be uncomfortable and embarrassing. But providing details about whom an exposed person has been with, for how long, where they were, etc., is essential to stopping the spread of COVID-19,” she wrote.

Oak Park and River Forest High School began the fall semester on Aug. 18, with all students learning remotely.

School spokeswoman Karin Sullivan said not all of the cases can be linked to the party. All 24 of the students who tested positive live in Oak Park. Sullivan said the school does not have specifics on how many students who live in River Forest might have tested positive so far.

“That number does not include any OPRF students who live in River Forest, which is under the jurisdiction of the Cook County Department of Health, who does not provide the district with the more specific type of information we get from the Oak Park Department of Public Health,” she wrote in an email to CBS 2.