Several Las Vegas Raiders players attended a charity event held by teammate Darren Waller that broke Nevada rules for the coronavirus pandemic and might have violated NFL regulations.

The Darren Waller Foundation held a fundraising event Monday at the DragonRidge Country Club in the Las Vegas suburb of Henderson, Nevada. The money being raised is intended to help young people overcome drug and alcohol addiction.

Players were seen on video without masks at the indoor event while talking and mingling with guests, who also weren't wearing masks.

The city of Henderson fined the country club $2,000 on Tuesday for four violations of the Nevada governor's COVID-19 emergency directives, including people not wearing masks and having more than 50 people at the event. The club has 30 days to pay or dispute the fine.

Among the players in attendance were quarterbacks Derek Carr and Nathan Peterman, tight ends Jason Witten, Foster Moreau and Derek Carrier, receiver Zay Jones and cornerback Nevin Lawson, as well as tight end Waller.

Rules from the NFL and NFLPA limit what players are allowed to do away from team facilities this season to try to prevent the spread of the coronavirus. Players are banned from attending any event that "violates local and state restrictions."

Raiders owner Mark Davis told the Las Vegas Review-Journal that the team is looking into what happened internally.

"We obviously take responsibility for this," Davis told the Review-Journal. "You don't like seeing this. I don't know that it's actually been built into our memories that you have to wear a mask. Our organization takes it very seriously."

The NFL and a representative from Waller's foundation didn't immediately respond to a request for comment.

This is the latest possible infraction of the COVID-19 protocols by the Raiders early this season. Coach Jon Gruden was fined $100,000 and the team was fined $250,000 because he failed to wear his mask properly on the sideline during a Week 2 game against the New Orleans Saints, sources previously told ESPN.

The team is also being investigated for allowing an unauthorized team employee in the locker room after the Saints game, ESPN reported Sunday.

Gruden said after the Saints game that he had the coronavirus in July and stressed that the team is taking it seriously.

Information from The Associated Press was used in this report.