Three police officers were injured during a confrontation with football fans after a match between AFC Bournemouth and Blackpool.
The trouble flared when a lone officer was struck on the back of the head as spectators were leaving the Kings Park stadium in Bournemouth on Wednesday.
A crowd then gathered preventing the arrest of the attacker and leaving two other officers injured.
Police chiefs have vowed to ban the culprits from future games.
Banning orders
They are now studying CCTV footage of the incident, which happened at about 2140 GMT and involved home supporters leaving the east stand.
Chief Superintendent Bob Boulton said: "This behaviour is most unusual at AFC Bournemouth matches and we have a long tradition of working very closely with the club.
"The chairman, Peter Phillips, has pledged his full support to the police investigation.
"Those responsible will be brought to justice, banned from the club and banning orders will be applied for, which will prevent their access to any football ground in the country."
One officer was left with a bruised head, another officer suffered a knee injury and a third has a hand injury.
Police have appealed for anyone with any information to come forward.