A black man pleaded for his life Friday as cops put a knee to his neck, punched him in the face, and the circumstances preceding the altercation are shocking.

The man, his cousin and a third person were passengers in a Lyft that was pulled over in Clayton County, Georgia ... they say it was pulled over because a tail light was out. They say Sheriff's deputies asked for his license but he didn't have one.  That's when they say a deputy asked to see the passengers' licenses. They asked the officers why they had to show ID since they had done nothing wrong.

There was clearly a confrontation, because the video starts with the man on the ground with 2 deputies on top of him. At one point, you see a deputy punch the man repeatedly in the face, drawing blood.

You hear a woman -- apparently the man's cousin -- screaming at the cops to stop punching, and the deputy responds, "He's biting my hand."

As the deputy continues to press the man's head on the pavement he screams, "I'm gonna die!" and "I can't breathe." The young child watches as the man on the ground appears to have been rendered unconscious.

We do not know if the man was injured. It appears he was arrested.

The Clayton County Sheriff's Office tells TMZ, "After being made aware of a video posted on social media involving a Deputy using physical force on a man, Sheriff Victor Hill ordered his entire Internal Affairs Unit to come in and begin an investigation that has been on going since 8pm. The Sheriff has ordered that the Deputy involved be placed on administrative leave pending the outcome of the investigation."