Blueface was stabbed during his boxing workout yesterday -- but we're told cops now have the man who they think is responsible for the attack in custody.
Law enforcement sources tell TMZ Hip Hop, 36-year-old Brandon Henry Snell was arrested and booked for felony assault with a deadly weapon Wednesday afternoon after turning himself in ... and is currently sitting in jail.
THE ALLEGED INCIDENT Instagram / @bluefasebabyy
You can see in the video, Blueface and a man get into a physical fight .