Brighton slammed the “minority” of Crystal Palace fans who “came intent on causing disorder” and left several stewards injured, including two in hospital.
Crystal Palace's trip to Brighton for the first Premier League M23 derby last night was marred by crowd trouble outside the ground.
Around 150 fans were refused entry at 7.51pm after a number of ticketless away fans tried to force their way in three minutes earlier, after the game had started, leading to the closure of the turnstiles.
Those who were locked out were instead escorted back to the nearby Falmer train station and eventually onto a train back to London.
Some Palace supporters managed to smuggle smoke bombs and flares while others also tried to get in with knives and knuckledusters.
Chief Inspector Simon Nelson, who also revealed masked gangs of rivals fans had clashed in the city ahead of kick-off, 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.”
Sussex Police have made six arrests, while the FA are in contact with both clubs and the police over Tuesday's ugly scenes.
Brighton's chief executive Paul Barber said: “Firstly, we hope the two stewards hospitalised in the disorder have not suffered serious injuries.
“The disorder was caused by a minority of individuals who attempted to gain entry to the stadium without tickets.
“Thanks to the swift action of the club’s stewarding team, supported by Sussex Police, we avoided further, major disorder - and while some genuine fans were left extremely disappointed and unable to get into the stadium, the correct decisions were made.
“I’d like to thank the majority of fans of both clubs for their good behaviour and patience in complying with the instructions of our stewards and police.”
Crystal Palace said in a statement: "We have been made aware of a small group of supporters attempting to gain access to the Amex stadium last night without tickets while using bangers and flares.
"This kind of antisocial and criminal behaviour is completely unacceptable and we condemn it in the strongest possible terms.
"There are very clear images of the incident and we will work with the police to identify the supporters involved, who will face stadium bans as well as potential criminal proceedings.
"We would like to apologise to all the innocent supporters who arrived at the stadium with tickets but were denied entry and to the two stewards who were injured at the ground. We wish them a full and speedy recovery."