Shelagh Fogarty is Leading Britain's Conversation.
24 April 2017, 10:09
Arsenal and Manchester City fans fight outside Wembley
The two groups clashed outside the ground after Aresnal beat City during extra-time of the FA Cup semi-final.
The footage, filmed from inside the ground, shows the two groups of fans, wearing red and light blue, squaring off against each other outside Wembley.
A woman watching says: "Oh no, there's kids down there."
After a few initial punches were thrown some fans appeared to try and calm the situation down. But others then ran in to restart the violence.
The woman watching later asks "Why would you punch a kid like that?"
Alexi Sanchez scored an extra-time winner to put Arsenal through to the FA Cup final in the dramatic 2-1 game.