9:52 AM PT -- The boy in the video allegedly punched his teacher in the chest and cops were called to his school, Gerald Adams Elementary, and arrested him on a felony battery charge ... this according to the police report obtained by TMZ.
The report says the kid cursed at the teacher and told her "my mom is going to beat your a**" before punching the teacher in the chest with his right hand. The teacher says it all started when the kid wasn't properly sitting on a bench.
The alleged incident happened on Dec. 14, 2018 and the status of the case is unclear. The video started circulating Monday and Key West Police Chief Sean T. Brandenburg told the Miami Herald his officers didn't do anything wrong.
Here's police in Florida scaring an 8-year-old boy into straightening up his act ... by slapping handcuffs on him and taking him to the slammer.
Civil rights attorney Ben Crump claims the boy Key West police tried to scare straight has special needs, and he's ripping cops for their tactics.
As you can see in the video, the young boy is so small his hands are too tiny for the cuffs and they fall off his wrists. Crump says the kid is only 3.5 feet tall and 64 pounds.
Police body cam footage also shows officers lecturing the boy as they lead him out of his elementary school and into the back of a squad car. Crump says the kid was then taken to a real jail for processing. Ya know, just like an adult.
U.S. politician Julian Castro also shared the shocking footage on social media, calling the incident "unbelievable" and saying "police should have no role in punishing our kids or pulling traumatic stunts like this on our schools."
We reached out to Key West cops to find out what led up to the arrest, but so far no word back.