Anthony Elanga recovered to seal victory for Manchester UnitedThe Football Association is investigating after Manchester United's Anthony Elanga was struck by an object thrown from the crowd in Sunday's Premier League victory at Leeds United.
There were also numerous unsavoury chants from both sets of supporters.
West Yorkshire Police said a total of nine arrests were made for offences which include the throwing of missiles.
While there was "no significant disorder" and no injuries were reported to any players or fans, the police said offences "including public order, throwing of missiles and breach of banning order" took place.
A group of 70 away fans turned up in Leeds without tickets and were issued with dispersal notices prior to the match.
In what was the first game in front of fans between the two old rivals at Elland Road since October 2003, Elanga scored his side's fourth goal with two minutes remaining to confirm victory for Ralf Rangnick's men.
Elanga needed to be attended to after being hit by missiles thrown from the crowdArrests at football matches across the top five English leagues are at their highest levels in years, with fan disorder "getting worse", according to the UK's football policing lead.
There were more than 800 football-related arrests in the first six months of the season and more than 750 reported incidents of disorder.
"As far as I know, there is some investigation going on from Leeds United. I don't think that anything happened in the end," said Manchester United's interim manager Rangnick.
"Elanga looked well and he was happy about scoring his goal. Obviously things like that should not happen and I think even more so this game. The atmosphere was great."
Leeds boss Marcelo Bielsa said he did not see the incidents involving objects being thrown, but he condemned such actions.
"Any excess other than sporting should not be approved," he said. "I can't evaluate what you spoke about because I didn't see it."
Leeds 2-4 Man Utd: Rangnick praises his players for showing 'successful' attitude'Vicious atmosphere at Elland Road'
Chief football writer Phil McNulty
Elland Road had waited 19 years to stage a game between Leeds United and Manchester United in front of fans and the poison contained in this bitter rivalry boiled over in a vicious atmosphere.
There was a heavy police presence around the stadium before, during and after the game, as well as in Leeds city centre hours after the game, such is the scale of hostility between the two sets of fans.
Inside Elland Road, the tone was set from the moment Manchester United's players came out to warm-up to chants of "scum" - but this a very mild message when compared with some of the truly vile verbal exchanges from opposing supporters throughout the game.
Manchester United's goals were the fuse for some of the worst excesses, with captain Harry Maguire and celebrating players being shepherded away from in front of the Don Revie Stand and angry Leeds fans after his opener.
Visiting supporters released red pyrotechnics, leaving the smell of fireworks hanging heavy in the air, but it was the last two goals scored by Ralf Rangnick's side that saw his players in physical danger as they were pelted with missiles.
Anthony Elanga needed medical treatment after Fred put Manchester United back in front at 3-2, with similar treatment meted out after the substitute, recovered after being struck, added the fourth himself.
The game itself was a classic played out in a deluge - which was so torrential and persistent it may have actually reduced the possibility of further trouble around Elland Road - but the atmosphere inside the stadium and the actions of supporters has now inevitably led to a full investigation.
