Two men were caught on camera fighting on a busy Dundee city centre street in broad daylight.
Police are now investigating the incident after an alarming video of the fight was posted on a social networking site.
The two men were filmed trading punches at about 1.30pm on the Nethergate, outside the Steeple Church on Tuesday.
When one of the men falls to the ground, the video shows the other man climb on top of him and appears to stamp and kick his victim.
The violent incident was posted on social media and has been shared more than 60 times.
Jo-Ann Weir, 26, who filmed the video while with her daughters two-week-old Willow and three-year-old Poppy labelled the attack “disgusting”.
She said: “The man who knocked him out was just sitting smoking a fag when this other guy walked up to him and started on him.
“He was shouting abuse and squaring up to him. They just started fighting it was disgusting.
“After the guy was knocked out, he got up soon afterwards and started running around with his top off asking other people for a fight.
“I left as soon as I could,” she said.
“He was part of a large group of people just hanging around causing trouble. There should be people patrolling to stop these folk.”
Speaking after the shocking event, a spokeswoman for Police Scotland said: “We are aware of the incident and will be looking into it.”