The NSW Police Force are investigating the arrest of an Indigenous teenager by one of their offices in an inner Sydney suburb on Monday.
NSW Police said officers were patrolling Wade Park in Surry Hills when they confronted a group of teenagers.
They said one of the teenagers threatened an officer.
A video posted on social media showed the police officer grabbing the teenager and 'sweeping' the boy's legs from underneath him.
The 17-year-old falls head-first onto paved ground and can be heard moaning with pain in the video.
A family member said in a post on social media that the teenager had sustained a bruised shoulder, cuts & grazing to his knee, face and elbow, and chipped teeth, and that they were awaiting the results of x-rays.
NSW Police have confirmed the arrest and have said the boy was taken to Surry Hills Police Station before being conveyed to St Vincent's Hospital.
"An investigation into the circumstances surrounding the arrest is now underway by officers attached to the Professional Standards Command," a statement issued by NSW Police said.
"The constable involved has been placed on restricted duties while this review is carried out.
"Senior officers have met with the community and local elders and will keep them appraised throughout the process."
The teenager's family is expected to make a public statement on Tuesday afternoon.