Manchester United boss Ralf Rangnick blasted Leeds fans after Anthony Elanga was hit by a missile as he celebrated scoring their third goal on Sunday.
The United players were also targeted as they celebrated Harry Maguire's opener and at half-time and Rangnick went on to the pitch to act as peacemaker when there was a melee.
"As far as I know, there is some investigation going on from Leeds United," said the United boss.
"Anthony Elanga looked well and was happy about scoring his goal. Obviously, things like that should not happen, this game, even more so.
"The atmosphere was great, at times we had to cool down things on the pitch.
"This is what I did when I walked onto the pitch, I didn't want anything to happen, no yellow or red cards. At times like this it's important to cool things down."
Leeds boss Marcelo Bielsa also condemned the missile throwing, saying: "Any excess other than sporting shouldn't be approved."
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