A 15-year-old girl was taken to hospital after violence erupted outside a Ballymena United match for the second time in weeks.
Police are investigating the incident near to Inver Park in Larne after a County Antrim Shield match on Tuesday night between the home team and Ballymena, which United won 3-2.
A police spokeswoman said: "At around 10.10pm it was reported a 15-year-old female had been injured following an assault. She was taken to hospital for treatment Police enquiries are ongoing."
A Northern Ireland Ambulance Service spokesman said it received a report of the girl being assaulted near to Larne and Inver School and she was taken to Antrim Area Hospital.
The girl was discharged after treatment.
The teen is understood to be a Larne supporter and was "badly shaken" by her ordeal.
It is not the first time elements of the Ballymena support has been involved in trouble.
On November 18 there were clashes between fans after a cup game between Ballymena United and Coleraine.
Both Larne FC and Ballymena United condemned the latest violence, which has also been slammed by football fans.
Larne FC chairman Archie Smyth called the incident "despicable" and said police told the club before the game a "small element" going to Ballymena matches were intent on trouble.
He added: "They are not true supporters and they marred what should have been a great night for the Ballymena fans who came to watch a game of football. We are now making moves to get in touch with this girl's family to ensure she is okay."
He added: "One of our stewards heard a commotion and he ran down to see what was going on and she was lying on the ground. Guys wearing Ballymena scarves had seemingly just attacked her.
"The Ballymena fans were at the bottom exit and our fans were coming from the top exit walking down the road and she must have run into them there at the War Memorial.
"For anybody to attack a wee girl of 15 is terrible. These were young lads. It leaves you just speechless."
Larne FC board member Lyn Kernohan said: "The Ballymena fans had been asked to park in the Riverdale car park but for some reason a bus parked in the church car park, which meant the fans kind of met each other.
"You couldn't even call them Ballymena supporters. I think the people who did this were in their mid-teens. The girl was hit in the head or face. We hope it doesn't put her off going to matches."
Ballymena United secretary Don Stirling said his club "want to disassociate ourselves from this small group of thugs".
He added: "They are not real football fans, they are just looking for an excuse to fight.
"Their actions are absolutely disgusting and I hope the face the full rigours of the law."
After trouble following the Ballymena versus Coleraine game in Ballymena on November 18, supporters condemned "rogue elements".
Two arrests were made on that date. There were reports from eye-witnesses of "hand-to-hand fighting" between supporters following the November game at the Ballymena Showgrounds.