Clarets' fans celebrations after Burnley beat Cardiff at home on Saturday was marred by trouble outside the ground after the game.
Fighting broke out on Harry Potts Way and the fracas was caught on camera by a Cardiff fan as they left the ground on a coach.
In the video a child appears to be hit and falls to the ground unconscious.
The footage was shared across social media and police have been made aware of it.
A spokesman for Lancashire Police said today: "We are aware of the video and are investigating what happened."
Burnley's 2-0 win eased any relegation worries fans had and there was a electric atmosphere in the stadium.