Lancashire Police are investigating fighting outside Turf Moor on Saturday following Cardiff City's Premier League defeat to Burnley.
Video footage taken from a coach of a brawl between fans was uploaded on to social media sites that appears to show a fan knocked out cold by a punch.
It also shows women caught up in the fighting, and one female on crutches, making her way through the middle of the trouble.
Local police have confirmed they are aware of the fighting and investigations are ongoing following the Bluebirds' 2-0 defeat.
Tensions were high at Burnley on the weekend with both clubs trying to secure their Premier League survival.
And Cardiff City's players and fans were left stunned after a major controversy during the game.
Everything a dejected Neil Warnock said after Cardiff City's controversial defeat to Burnley
Manager Neil Warnock was apoplectic after referee Mike Dean reversed a decision to award the Bluebirds a penalty early in the second-half as they trailed their relegation rivals 1-0 in a game they could not afford to lose.
In a bizarre passage of play, Harry Arter's shot was blocked by Ben Mee's arm before Mee headed the ball onto his arm from a Joe Bennett cross in a separate incident moments later.
Referee Dean blew for a penalty before changing his mind after consultation with his assistant.
It was initially unclear which incident was actually penalised and whether the referee or linesman awarded it in the first place.
The decision sparked angry scenes for several minutes as Cardiff's players confronted Dean, while Warnock was seen remonstrating with the fourth official.
The first of the two incidents appeared to be the more clear handball, but Dean seemed to penalise the second before changing his mind amid confusing scenes.
