The P.S.N.I. has issued a warning about a video of a "nasty assault" in Derry.
P.S.N.I. issued the appeal on Friday morning when people began to report the incident on social media.
"We have a lot of people on line reporting an assault at Union Hall Place in Derry/Londonderry last night [February 21]," said police.
"This has not yet been reported but there is a video circulating showing a pretty nasty assault."
The police urged anyone witnessing such an incident to dial the emergency number immediately.
"If you see something like this please please please ring 999 at the time.
"If you saw a house on fire you wouldn’t message NIFRS, likewise if you see an assault don’t message us, RING 999!!! The victim has walked away from this one but remember that one punch can kill."