Updated 07/14/14 – 1:20 p.m.

CHICAGO (CBS) — Two men were charged with throwing bottles that struck police officers who were breaking up a large fight at Montrose Beach on Sunday, and three other men were charged in connection with the melee.

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Efrain Saucedo, 23, and Emmanuel Lopez, 19, both of Aurora, have been charged with one count each of aggravated battery to a police officer. Chicago police said they were seen throwing bottles during a disturbance in the 4400 block of North Simmonds Drive, in the park just west of Montrose Beach.

Efrain Saucedo (left) and Emmanuel Lopez (right) are charged with throwing bottles at police officers during a brawl at Montrose Beach on July 13, 2014. (Credit: Chicago Police)

Efrain Saucedo (left) and Emmanuel Lopez (right) are charged with throwing bottles at police officers during a brawl at Montrose Beach on July 13, 2014. (Credit: Chicago Police)

At 7:37 p.m., Chicago police responded to calls of a fight in progress at the beach, where a large crowd — possibly as many as 300 people — had gathered for an unlicensed party. It was unclear what started the fight, but the beach was pure chaos when officers arrived. Many in the crowd turned against police, and started throwing objects at the officers – including two officers who were hit by bottles. One of the officers went to the hospital, the other refused treatment at the scene.

“A lot of people started beating up the cops, too. They started throwing beer cans. I don’t know, it just got crazy,” witness Ivan Hernandez said. “They were just throwing beer. They started smashing police car windows and stuff. You know, just how people get when they get drunk.”

Police had the park under control by about 9 p.m., and police shut down the illegal party and closed the beach early due to the incident.

In addition to Saucedo and Lopez, at least seven other people were taken into custody. Of those, two young men — a 19-year-old from Summit, and a 22-year-old from Aurora, were charged with misdemeanor aggravated assault to a police officer and misdemeanor mob action. A 17-year-old male from Chicago was charged with misdemeanor mob action and felony property damage. It was unclear if the four others who were arrested would face charges.

Hernandez said several officers pulled out stun guns as they tried to put a stop to the brawl. As officers were trying to break up the fight, a call went out over the police radio with a dispatcher reporting a possible gunman in the crowd. However, no gunshots were fired during the incident.

A police helicopter was sent to the scene as SWAT teams and officers from several districts responded to disperse the crowd.

Police said at least one squad car was damaged during the melee.

One officer who was struck by a bottle was taken to Weiss Memorial Hospital, and was treated and released Sunday night. Another officer struck by a bottle refused medical treatment at the scene. Sources said at least two other officers were injured while quelling the melee, but did not require medical treatment.

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Trash was everywhere at the beach after the park was closed, including lots of leftover food, empty beer cans, and broken glass.

Park District workers spent three hours using rakes, shovels, and pokers to pick up trash strewn across the park.

One worker quickly noticed a theme to the litter: beer and liquor bottles.

“I don’t know where security was at the time, but nobody’s supposed to have alcohol in the park, but that’s all you see,” Park District worker Debra Castanedo said.

Without a valid permit, alcohol is banned at all Chicago parks and beaches. The Park District said Sunday night’s concert did not have any permits.

Cleanup crews got help from scavengers collecting the empty bottles and cans.

“One pound, fifty cents,” Mike Zivkovick said. “I make maybe 200 pounds or more. … A hundred dollars is good to me.”

One woman who came to the beach Monday morning to walk her dogs was shocked to see the mess of discarded food, broken bottles and empty beer cans.

“I’ve seen it bad; really bad, but this is the worst. I thought it was a staging for something,” such as a movie, Marlene Bennett said.

Nelson White also said he was “shocked” at how much trash was left behind.

“Never seen so much litter and garbage here,” he said.

Crews got the mess cleaned up before a brief spate of rain Monday morning.

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The Park District said Montrose Beach would open as normal at 11 a.m. Monday. The park area opened earlier in the day, as usual.