AUSTIN, Texas (CBSDFW.COM/AP) — About 300 teenagers were exposed to the coronavirus at a massive party in a posh lakeside suburb in the Central Texas hills, Austin Public Health authorities said.

High school students partied at the Pongfest in Lakeway on Saturday, June 20, said Sandy Cox, mayor of the community about 20 miles west of Austin.

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Some of the partygoers were awaiting test results for COVID-19, when they attended the party and have since tested positive for the virus, Austin Public Health said Friday in a statement.

“The virus often hides in the healthy and is given to those who are at grave risk of being hospitalized and dying,” the health officials said. “While younger people are at less risk for complications, they are not immune to severe illness and death from COVID-19.”

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Cox said in a Facebook Live announcement that anyone who attended the party should self-isolate and disclose their participation if contacted by contact tracers. The incident is being investigated by Austin contact tracers.

“Unfortunately, our case load is very probably going to increase,” Cox said.

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