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The Sacramento Police Department on Tuesday announced a formal investigation into the actions of one of their officers who was seen slamming a black man to the ground and beating him — all sparked by an alleged case of jaywalking.

The video, released Monday, has sparked national outrage. It shows the officer confronting the man, identified as Nandi Cain Jr., as he crossed an intersection and attempting to talk to Cain but the situation quickly escalates.

After some words are exchanged while Cain is standing in the street, the officer then violently throws Cain to the ground and begins to punch him in the head.

The events leading up to the incident were not captured by the camera, and it is not possible to hear the conversation between Cain and the officer before the incident occurred.

Bystander Naomi Montaie, who took the video and posted it on Facebook, can be heard screaming, "Oh my God! Why’d you take him down like that? No! That was wrong!"

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Montaie filmed the five-minute-long video as the officer called for back-up. Six additional officers arrived to assist in Cain’s arrest.

In a statement, the Sacramento Police Department said the officer originally "attempted to detain a pedestrian for allegedly unlawfully crossing the street."

Cain then "questioned the officer’s validity to stop him at which time a violent encounter occurred between the officer and the pedestrian," the statement continues.

"For an unknown reason, the officer threw the pedestrian to the ground and began striking him in the face with his hand multiple times," the SPD statement said.

Cain was initially charged with resisting arrest but it was later dropped and he was released, officials said.

He told NBC affiliate KCRA that he thought he was going to die.

"I thought I was going to be like the next Trayvon Martin," he said. "I felt like they were going to draw a gun out and shoot me in my back or try to break my arms off or something.

"It was supposedly for jaywalking," Cain said of the initial arrest. "And then, when they put me in handcuffs and they were driving off, I heard them (talk) about they were going to get me for resisting arrest. But as you can see on the video clearly, I didn’t resist at all."

In addition to the video posted on social media, Sacramento authorities are reviewing footage from a camera inside the patrol car.

“The videos of this incident portray actions and behavior that we would consider unacceptable conduct by a Sacramento Police Officer,” the department said.

The Internal Affairs Division is investigating the incident and the officer involved was placed on paid administrative leave, officials said.