Rangers head coach Danny Röhl has condemned the pitch invasion after Celtic's Old Firm Scottish Cup win at Ibrox, as the Scottish FA confirmed an investigation would be carried out immediately.
Celtic progressed to the semi-finals with a 4-2 shoot-out victory over Rangers after the goalless draw at Ibrox, which sparked a pitch invasion from both sets of supporters.
Missiles were thrown as police and stewards moved to form a barrier between the two sets of fans. Order was then restored as the 7,500 Celtic supporters were left to celebrate alone.
The Scottish FA quickly condemned the fans' behaviour and said "an investigation will be carried out immediately".
Speaking in his post-match press conference, Rohl said: "I was not on the pitch in the moment; I did not see it until now. I think we all know the emotional situation after a game. Nobody likes to see this.
"It was a great atmosphere for 120 minutes and it should be like this; the other things should not be in the stadium or in football."
O'Neill provides more details on pitch invasion
Celtic players were escorted off the pitch as the chaos ensued, with manager Martin O'Neill providing further details after the game.
"It's a big derby game and I think there was a lot of jubilation at us winning. The fans spilt over and I suppose it is very difficult to quell that," O'Neill said.
"As we were making our way back, there was some kind of fracas and someone had tried to get on the field. It's unfortunate [scenes at the end] but hopefully it doesn't dilute the performance in terms of character.
"All I saw was a bit of a scrum down at the bottom. As you say, maybe it does taint proceedings but I think there was an element of self-protection in that one.
"I am making judgments on things I only half saw. From my viewpoint, it was a great win for us. Rangers are very strong and had the full week to go at it."
O'Neill worried pitch invasion will overshadow Old Firm win
On whether the pitch invasion from supporters would overshadow the victory, O'Neill added: "That would be a worry for me.
"The fixture itself, although still a phenomenal fixture, had lost a bit of its lustre because the away fans or the full complement of away fans were not allowed in.
"I have no idea what might happen. I think today, with the crowd and our crowd there, to me, it was a proper Old Firm game in that sense. We will see what develops."
Old Firm clashes a 'disgrace', says Adam
Former Scotland international Charlie Adam labelled the pitch invasion a "disgrace" and said both sets of supporters let themselves down at Ibrox.
"It's a disgrace," he said on talkSPORT. "It's a sad day for Scottish football.
"For the Old Firm that we talk about being our leadership teams and (what) they represent, it's an embarrassment for our game.
"And as a national team we're trying to improve and we're trying to get better. But these two clubs have let us down as a nation and they have to have a look at themselves today.
"Both football clubs have to look at themselves because they are the standard-bearers for us as football clubs and they have, both (sets of) supporters have let themselves down.
"It's an embarrassment for Scottish football. This should not be happening. In this day and age this should not be happening and we have to get control of it quickly because if it doesn't it'll keep escalating and escalating and there'll be big, big problems."