Watch: Violent scenes as rugby fans brawl on pitch
Police are appealing for more information on the crowd trouble that marred the Million Pound Game in Hull.
Two men were arrested in the aftermath of Salford's dramatic 19-18 victory over Hull KR at Craven Park which ensured they remain in Super League at the expense of their hosts.
Fans had to be cleared from the pitch at the end of 80 minutes to allow extra time to be played and stewards and police officers had to intervene to break up violent clashes between rival fans following another invasion after the final whistle.
Police made one arrest amid the ugly scenes, while a second man was arrested on suspicion of assault following a further altercation close to the Wolseley Medical Centre near the Lightstream Stadium.
Humberside Police match commander, Superintendent Tracey Bradley, said: "Officers quickly dealt with the disorder following the match, bringing the incident to an end within minutes.
"Violence and disorder will not be tolerated and arrests have already been made in connection with the incident.
"However, we would also appeal for anyone with information about the identities of those involved to get in touch."
The incident is a huge embarrassment to rugby league which prides itself on being a family game and the governing body, the Rugby Football League, promised to launch its own investigation into the disturbing scenes.
"Games with so much at stake often mean emotions run high, but that does not excuse the minority of fans who behaved unacceptably following the final whistle," said RFL chief executive Nigel Wood.
"The RFL will conduct a full investigation into these incidents and will work with the police and club involved to ensure anyone found to have acted violently is dealt with appropriately and also banned with immediate effect."
The incident comes as Salford wait to discover their punishment for crowd trouble at the end of their Super League match at Huddersfield on Easter Monday.
Salford owner Marwan Koukash played down the seriousness of the trouble in Hull.
"I ran onto the pitch myself," Koukash said. "I wouldn't say I had the right to either, but I was standing with our bench.
"I saw bits and pieces of what happened but I was engulfed by fans who were celebrating our victory.
"The fans were wrong to run on but emotions were running quite high on both sides, I don't think Salford fans were the ones that started the fight. They had no reason to want to fight.
"I don't condone the actions of the fans running onto the field but it was an exciting finish to a rugby game and let's celebrate that."