PITTSBURGH (AP) — Public safety officials broke up 15 fights, ferried 34 people to hospitals and responded to at least 150 emergency calls related to a Luke Bryan concert in Pittsburgh, Mayor Bill Peduto said Sunday in calling for event organizers to pick up part of the tab.

About 50,000 fans descended on Heinz Field for Saturday night's show by the country superstar. Tailgaters arrived up to nine hours before the event, leaving behind mounds of trash in parking lots, surrounding neighborhoods and in the Allegheny River, Peduto said.

At least seven people were arrested, and public works employees were still cleaning up Sunday morning, Peduto said in a statement.

"The continued trashing of our city has to stop," Peduto said. "There is no reason ... (for taxpayers) to bear the burden for outsized amounts of garbage removal and public safety response."

The aftermath appeared less overwhelming than the mess left after a Kenny Chesney country concert last year, when crews hauled off more than 45,000 pounds of garbage, according to public works Director Mike Gable. More than 70 arrests were made related to that show.

While acknowledging the economic benefits of big concerts, the mayor said the city will begin billing promoters and related private parties for public money spent on cleanup and safety efforts. Representatives for the stadium's parking lot management company and Bryan's promoter were not available to comment.

Tailgaters on Saturday were given trash and recycling containers, which appeared to help.

"It's definitely cleaner than it was last year. People aren't just throwing their trash on the streets. They're using the bins and bags," Ryan Callahan, 25, of Delmont, told the Tribune Review on Saturday.