SAN FRANCISCO (CBS SF) — An arrest caught on video at a BART station in San Francisco has sparked outrage on social media and a protest.

Witnesses and BART officials tell two very different versions of the story.

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At least two witnesses videotaped the chaotic scene at the Embarcadero station and posted it on Facebook.

In one video, shot closeup, at least four officers are restraining the suspect on the ground. In another, passengers can be heard yelling at officers to “let him go.”

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One witnesses claims the suspect was playing around with a friend on the train when an annoyed male passenger called the police. She said the arresting officer pulled out a gun at one point.

BART officials dispute that version of events and say the arresting officer acted appropriately.

They said officers responded after the suspect threatened to rob another passenger, and he physically fought back when the officer tried to arrest him.

A group of people returned to the Embarcadero station on Saturday afternoon to stage a protest.

BART’s Internal Affairs Division has launched an investigation into the video.

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Meantime, the suspect was booked on two counts of resisting arrest and five counts of battery on a police officer.