**Correction: A previous version of this article misspelled the last name of epidemiologist Brian Hartl. We regret the error, which has been fixed.

FOREST HILLS, Mich. (WOOD) — The Kent County Health Department has tied several COVID-19 cases to graduation parties in the Forest Hills area.

The health department believes a large gathering two weeks ago is causing teens to test positive for the virus. They’re calling it the largest coronavirus cluster in the county associated with a private event.

“It raises the risks of transmission within our community when we’ve got a cluster of cases, so there may be people who have been exposed and don’t know it,” said Brian Hartl, an epidemiologist with Kent County.

Starting on Sunday, the positive COVID-19 cases were passed on to the Kent County Health Department.

“Some of these were in zip codes where we haven’t seen a lot of cases over the course of the last couple months,” Hartl said. “So, that starts to raise our interest about what is going on there.”

That zip code was the Forest Hills area.

Through interviews with 21 people who tested positive, the Kent County Health Department learned they all attended graduation parties or an after party the weekend of July 18.

One of those parties was held at the Watermark Country Club. The after party was at a private home.

The other graduation party was at an unknown restaurant.

Watermark declined to comment on the party. A staff member told News 8 that once the party moved inside, guests did not wear masks or practice social distancing.

Forest Hills Pediatrics posted on its Facebook page saying: “We are getting a large volume of calls regarding COVID exposures. We are aware of several large events that seem have to been the source of outbreaks. We are responding as quickly as possible but this is stressing our office system.”

“We are not pointing fingers at this particular event, but it just shows the potential when people get together and gather, there is a risk,” Hartl said.

The health department is reminding people who gather to practice social distance, limit the number of hands on any food and keep sanitizer around.

“We want people to gather and still be social, but we want them to do it in a safe way to protect themselves and protect others who are attending,” Hartl said.

On Wednesday, Gov. Gretchen Whitmer announced that gathering will be limited to 10 people statewide for indoor gatherings and up to 100 people for outside events. Previously, indoor gatherings in the Traverse City and Upper Peninsula regions were limited to 50 people.

The Kent County Health Department is stressing space is needed to allow for all guest to social distance.