Police are working to identify a man who ran on to the pitch at a Championship football match and violently slapped a goalkeeper.
Sheffield Wednesday's Chris Kirkland required medical treatment after being attacked by the Leeds United fan during last night's game.
The incident occurred shortly after Kirkland conceded an equaliser at Wednesday's Hillsborough Stadium.
The man was one of a number of Leeds' fans who ran on to the pitch in celebration. He slapped Kirkland in the face with both hands, knocking him to the floor. The match, which was televised live on Sky Sports, finished 1-1.
Leeds United has condemned the attack on Kirkland
Chief Superintendent Jason Harwin, of South Yorkshire Police, said a senior investigating officer would be working with a team of officers to identify those responsible for the disruption.
He said there had been five arrests for various offences including public order before and after the game, while three people were ejected from the ground and 12 were subject to dispersal orders.
In a statement released late last night, he added: "First I would like to thank members of the public who have contacted us with information to help in the ongoing investigations following the incidents at Hillsborough tonight.
"Fans have now left the city and there has been no further reported incidents of violence and disorder."
Earlier he said there had been several incidents where seats and bottles were believed to have been thrown inside the ground.
Leeds issued a statement after the game pledging to hunt down the man involved in the incident.
It read: "Leeds United Football Club would like to publicly apologise and condemn the action of the fan who came on the pitch and attacked Sheffield Wednesday goalkeeper Chris Kirkland. The club will fully co-operate with the police and the football authorities in identifying the individual concerned.
"After the week football has endured there is no place for this type of behaviour and the majority of Leeds supporters will be ashamed of his actions."
A large number of the Leeds fans housed in the Leppings Lane End sang about child abuse charges dropped against Wednesday manager Dave Jones.
The Wednesday fans also stoked things up with songs about two Leeds fans killed in Turkey in April 2000. Leeds supporters responded by throwing bottles onto the field and clashing with police.
Jones called for Leeds fans to be banned from "every away ground".
He went on: "You talk about racism, the chanting, that's a form of racism. And then (for the Leeds players) to go and wave at them... not in my book. You don't wave at them after that.
"I thought it had gone out of our game. The authorities have to look at it and sort it. I'm talking about an incident when we should be talking about the football. We're talking about vile animals. That's what they are. We talk about racism, but that, we need to sort that."
Anyone with information is asked to call police on 101 or Crimestoppers on 0800 555 111.