Police officers say they are investigating an incident at Corby Town FC on Saturday (March 12) where an opposition fan was punched in the face and ended up on the ground.
Footage of the incident has been shared widely on social media, leading the club to issue a statement condemning a 'minority of fans'.
The Steelmen were at home to Halesowen Town in their Northern Premier League Division fixture on on Saturday afternoon when the incident occurred.
Video shot from the terrace shows a group of away fans from the West Midlands town walking along the concourse past the home supporters carrying a flag that says 'We Live and Die This Town'.
They are followed by a male in a tracksuit with his hood pulled up, who appears to be a home supporter, who attempts to pull the flag out of their hands.
The away supporter can then be seen gesturing at the home fans before another CTFC fan then runs to him and punches him in the face. He then starts to move backwards before a second home fan punches him at least twice, and a third fan begins to attack him after he falls to the ground.
Other CTFC fans try to stop the scuffle along with a steward, and club mascot Robbie the Raven can be seen trying to avoid the melee.
The man's injuries have not been revealed by the club.
A statement issued by CTFC said: "We would like to thank the 602 fans from both sides who created a fantastic atmosphere at Steel Park on Saturday in our clash with Halesowen.
"It is with regret that a minority of less than 1 per cent behaved in a way that is unacceptable and sadly put a dampener on an otherwise enjoyable afternoon.
"Corby Town are passing on all information to Northamptonshire Police and as this is an ongoing investigation, we are unable to comment on any specific events.
"The club can confirm that action will be taken against those Steelmen supporters involved and we are fully cooperating with Northants Police.
"Anybody who acts in a manner that goes against our club guidelines are not welcome at Steel Park and we will not have the 99 per cent of well behaved fans in attendance tarnished by your behaviour."
No arrests have yet been made.
A Northamptonshire Police spokeswoman said: "We are aware of some trouble at the game and are working with the club to investigate the incident."
Separately, Halesowen Town have banned a number of fans from travelling on official supporters' coaches following racist chanting on the way back from Saturday's game. The group will also be subject to 'strict' conditions when visiting the Grove.
A club statement said: "Racism has no place in society let alone in football, and we are disgusted that a very small minority of people see it necessary to behave in this manner.
"Travel bans aboard our official coaches have been handed to those identified, and investigations continue to identify others involved, and the identity of those people have been sent to the remaining away clubs we have to visit this season, as well as strict conditions placed on any future visits to the Grove.
"Anyone found to act in an anti-social manner or that makes racist or homophobic gestures will be banned from the Grove – zero tolerance.
"We are extremely grateful to our fans that stepped forward and reported this incident on Saturday and we apologise to our true supporters who had to witness and listen to this appalling behaviour.
"We have always promoted the Grove as a safe place for supporters of both teams to come without fear of bigotry and we pride ourselves as being a very family friendly club."
Saturday's game ended in a 2-2 draw.