Ethan Miller, Getty Images

Kenny Chesney's concert at Heinz Field in Pittsburgh on Saturday (June 22) ended with public brawls, fans being treated for injuries, and a massive effort to clean up all the debris left behind by 50,000 fans. Nearly 75 people were arrested inside and outside the venue for various offenses, including disorderly conduct, public intoxication and aggravated assault.

KDKA in Pittsburgh reports that trouble began early in the day, when Chesney's fans -- dubbed the No Shoes Nation -- showed up to the venue before the gates were scheduled to open, causing massive traffic snarls.

The problems escalated as large groups of fans tailgated in the parking lot before the show, leaving behind a huge debris problem in their wake. The mixture of alcohol, crowding and general excitement contributed to at least 10 large fights breaking out, with 150 people being treated on-site for various medical needs. Another 45 fans were taken to medical facilities. 49 people were arrested inside the venue, and another 29 were arrested nearby.

"You probably could say 80 to 90 percent of the people there are acting responsibly, but even 20 percent of 50,000 people getting out of control is pretty bad," says Merril Stabile, president of ALCO Parking, which headed up the enormous cleanup efforts. "The Kenny Chesney crowd is the most difficult crowd for our staff to work with of any of the events of the year."

The next scheduled date for Chesney's No Shoes Nation Tour is at Verizon Wireless Amphitheater in St. Louis on June 27.