The University of North Carolina has suspended the football program’s voluntary workout program after 37 players and staff tested positive for Covid-19.

The Orange County Health Department in North Carolina determined the number of results to be a cluster forcing the Tar Heels to halt activities. The school says it administered 429 tests to players, coaches and staff with roughly 12% returning positive for coronavirus.

The university did not disclose the severity of symptoms of the 37 people who contracted the virus.