Wisconsin health officials said that nearly 500 cases of COVID-19 were linked to the outdoor celebration of the NBA’s Milwaukee Bucks championship parade, multiple news outlets reported.

During a daily COVID-19 briefing on Tuesday, Milwaukee Health Commissioner Kirsten Johnson confirmed 491 positive cases from the event, adding that the parade may be the leading factor of the recent rise of cases in the city.

Johnson also said this will lead the state to boost their contact tracing program. She called the 155 percent rise of COVID-19 cases in a week very “distressing,” according to The Washington Post.

“We encourage anyone who has attended a large gathering, such as the watch party in the Deer District, get tested for covid-19 due to the increased risk of transmission,” Johnson said. 

As many as 65,000 people were in the streets surrounding the arena where the Bucks play when they clinched their series win over the Phoenix Suns. 

The COVID-19 delta variant was already sweeping through the country at the time, leading to tens of thousands of new cases of coronavirus. The new delta wave has hit younger people who were not vaccinated particularly hard.

The Urban League of Greater Madison President and CEO Ruban Anthony told ABC affiliate WKOW in July that many people let their “guard down” during the celebratory events. 

“In terms of the Bucks event, there are a lot of people there and sometimes with celebratory events, sometimes we let our guard down,” Anthony said.

The Hill has reached out to the NBA for comment.