Gov. Phil Murphy is warning New Jersey residents, especially young people, that now is not the time to hold large summer house parties.

The governor says that large, indoor house parties are leading to a rise in COVID-19 cases.

“Folks, we cannot – we simply cannot continue to have crowded house parties. They are not safe. Period,” Murphy said Wednesday during his coronavirus briefing.

Murphy’s plea comes days after police dispersed over 700 people from a Jackson Township mansion in a party advertised on social media. It also comes after over three dozen Harvey Cedars lifeguards tested positive for the virus.

“[These parties] are how coronavirus gets passed around more efficiently,” Murphy said. “They put the hard work we’ve all undertaken together – the millions of us – at risk.”

The governor pointed out that COVID-19 is more easily transmitted indoors. And with bars and restaurants closed for indoor service, many are taking to partying underground.

“I get it. We get it. We’ve all had our routines turned upside down for the past four months and we want to blow off some steam with friends. None of us can fault anyone for having that notion,” Murphy said. “Just because you are younger and hopefully less susceptible to the ravages of COVID-19 is not an excuse to let your guard down. You are not immune.”

New Jersey, New York and Connecticut have joined forces to try to slow the spread of the virus in the Northeast. All three states have travel restrictions relating to 34 states, the District of Columbia and Puerto Rico. Travelers must self-quarantine for 14 days if they travel to New Jersey, New York or Connecticut.

Delaware remains on the travel advisory list, despite protests from the state’s governor. Persichilli said that one case of COVID-19 is linked to travel from Delaware.