CHICAGO (CBS) — Crews undertook a massive cleanup effort in Grant Park Monday, after the four-day Lollapalooza music festival wrapped up Sunday night.

Lollapalooza turns Grant Park into a playground every summer, with hundreds of thousands of people packing Hutchinson Field for music, food and much more.

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The cleanup started just hours after the last performer, Ariana Grande, took the stage on Sunday night.

After the huge crowds left Grant Park, crews moved in to pick up trash littered all over the park, to take down sound and lighting equipment, and begin dismantling the stages.

In the past, cleanup efforts have cost hundreds of thousands of dollars. In 2016 it cost more than $450,000 to clean up all the trash and repair the lawns, after extensive damage from the crowds and heavy rains, and an added day of music for the festival’s 25th anniversary.

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It’s unclear if the lawns will require any repairs this year, but there wasn’t any rain over the weekend, so damage to the grass should be minimal.

Meantime, city officials said 89 people were taken to hospitals during the first three days of the festival, largely due to alcohol-related problems.

A 24-year-old man who suffered a medical emergency on Saturday night later died at the hospital. He was identified Monday as Benjamin Seto of Falls Church, Virginia.

Further information on the medical emergency was not provided.

Authorities said 23 people were arrested during the first three days of the festival, mostly on drug-related charges.

There was also one gun arrest near Lollapalooza on Friday evening, but not on the festival grounds, when an undercover Chicago Police officer found three men running near the 11th Street Bridge and saw one of the men take out a gun and throw it under a bush, according to the city’s Office of Emergency Management and Communications. Another man in the group picked up the gun and was arrested by police after a chase, the OEMC said. A fully loaded 9mm gun was recovered.

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Ten other people received city citations at Lollapalooza; mostly for trespassing, and one for illegal use of a drone.