CHICAGO (CBS)–A Facebook video of a Chicago police officer engaged in a heated moment with two black men has prompted the Civilian Office of Police Accountability (COPA) to open an investigation into the officer’s actions, the agency said Monday.

The video, shot by a man with his friend, shows the two men talking with a police officer driving by them in an unmarked vehicle on July 4.

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The police officer pulls up to the men and asks them not to film him after they exchange a few words. When they continue shooting the video, the officer gets out of the SUV and starts walking with them through a park in the Auburn Gresham neighborhood.

“We’re going to the park,” one of the men says. He claims he’s shooting the video for a college project.

“Hey, let’s go–we’re gonna play at the park,” the officer replies.

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“Don’t try to film me, dude,” the officer is heard saying before he gets out of his vehicle. Early on in the video, another voice is heard saying “I kill mother (expletive),” but it’s unclear who is speaking.

As the three men walk through the park one of them asks the officer why he’s not wearing his badge.

He replies that his last name is Hunt and gives his badge number.

The men question his claim and he presses the men to call his supervisor.

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A video of a heated verbal exchange between 2 men and a Chicago cop has sparked an investigation.