The Chicago Cubs and Chicago White Sox are playing a rare crosstown series that actually matters this week at Wrigley Field. The White Sox are MLB’s biggest surprise this season, entering the week in first place in the AL Central with a 5.5 game lead over three other teams. The Cubs are the NL’s top wildcard team at the moment, and are hoping to chase down the Milwaukee Brewers for the division title by the end of the regular season.

Tensions were high in the first game of the series, and not just on the field. The Cubs beat the White Sox, 7-5, thanks to a dramatic 10th inning walkoff homer from possible MVP Pete Crow-Armstrong. The two teams traded the lead back and forth all night, with the Sox striking first on a three-run blast by Randal Grichuk, the Cubs forging ahead on a throwing error by Miguel Vargas, and then the Sox coming back on an eighth inning pinch hit home run from Andrew Benintendi.

It felt like a playoff game in mid-August, but unfortunately some fans couldn’t control themselves. There was a large brawl in the middle of the Wrigley bleachers during the game between fans. These were adults involved, but their actions were childish. Watch the video of the fight below.

Here’s another angle as security guards stood by and watched a Cubs fan get beat by a Sox fan.

PCA commented on the fight after the game, saying “you have people in the stands competing, too.”

The Cubs moved to 20 games over .500 with the win at 73-53. The Sox were the worst team in baseball history two years ago (41-121), but they now sit at 65-59 after Monday following thanks to a remarkable turnaround this season.

Cubs vs. White Sox is fun again, but some drunk, dumb fans threaten to ruin it for everyone else around them. These are adults, and they need to start acting like it.