A pitch invasion towards the end of the match temporarily held up Aston Villa's FA Cup quarter-final win over West Bromwich Albion.
Referee Anthony Taylor was forced to halt the game in stoppage time, with Villa leading 2-0.
The match resumed after a short delay, before another pitch invasion after the final whistle.
Villa, who advance to the semi-finals at Wembley, could now face a Football Association enquiry.
One fan is held by a steward at Villa Park
The hosts Villa secured the win with second half goals from Fabian Delph and Scott Sinclair.
Aston Villa goalscorer Fabian Delph: "My armband got nicked, someone got my left boot, but I could appreciate the relief the fans are feeling after a result like that.
"It was dangerous. Someone tried to take my boot off. People tried to kiss me and were biting me. It was scary."
A police line kept Aston Villa fans away from where West Brom's travelling supporters were seated
Match of the Day Live pundit Mark Lawrenson: "Why would you do this? You're winning, absolutely stupid. Loads of villages have lost their idiots tonight. Absolutely bonkers.
"It's like a scene from the 1980s all over again. Absolutely ridiculous."
"The ill-feeling between these two fierce West Midlands rivals provided a tense undercurrent throughout and boiled over in a threatening atmosphere over the final few minutes.
Hundreds of Villa supporters ran on to the pitch at the end
"West Brom fans, angered by Claudio Yacob's unjust red card and a second Villa goal from Scott Sinclair, threw several seats they had ripped out on to the pitch.
"The response from Villa fans was that premature pitch invasion, although it should be stressed it was a minority and thousands of their own supporters vented their fury against them.
"It was, in fact, only a minority on both sides but still a poor advert for the game, right down to West Brom sub Callum McManaman reacting angrily to being jostled by Villa fans at the end."
Aston Villa are into the FA Cup semi-finals for the first time since 2010