Violent scenes that took place in and around Brighton and Hove Albion's match at home to Crystal Palace on Tuesday have been described as a "return to the dark days of football" by police.
Tuesday's goalless draw in the Premier League was overshadowed by hooliganism in and outside south coast club Brighton's Amex Stadium ground.
Brighton and south London side Palace have a history of bitter rivalry dating back to the 1970s.
According to Brighton, some Palace fans who travelled without tickets attempted to storm their way into the ground, with police saying "groups of masked people" sought confrontation as supporters tried to enter the Amex with "pyrotechnics, knives and knuckledusters".
Chief Inspector Simon Nelson of the local Sussex Police force also added that at one point a large number of people, seemingly without tickets, over-ran turnstiles in the south stand of the ground in a bid to force their way into the away supporters' section.
There were also disturbances at Brighton railway station as frustration increased among fans who realised they would miss the start of the match.
Six people, including a 15-year-old boy, were arrested, while two stewards -- one from each club -- had to be taken to hospital, one with three fractured ribs.
Both stewards were discharged later on Tuesday.
While football violence in England is nowhere near the levels it was during the 1970s and 1980s, incidents do still take place, although it is increasingly rare for there to be trouble in and around grounds.
But a concerned Nelson said: "I have been involved in football policing at all levels and have been a match commander for Albion matches for 12 years, but I have never come across such concerted attempts to cause disorder and engage in violent behaviour.
"This was a return to the dark days of football and is not acceptable."
Palace said Wednesday that any of their supporters who were involved would face stadium bans.
"This kind of antisocial and criminal behaviour is completely unacceptable and we condemn it in the strongest possible terms," said a club statement.
Brighton closed their turnstiles six minutes into the match at 7:51pm (1951 GMT), which meant some fans who were left outside the ground and escorted back to the railway station.
Palace said fans who had legitimate tickets but were unable to watch the game would be eligible for a refund.