Football bosses have called for action to stop "dangerous" pitch invasions after violence broke out at the end of an Everton v Crystal Palace match.
Palace boss Patrick Vieira kicked an Everton fan who goaded him on the pitch at Goodison Park after the home side won 3-2 on Thursday.
Police said four men were arrested and one officer was treated for smoke inhalation after flares were set off on the pitch. And during the match, an Everton fan seemed to slap Palace player Joachim Andersen on the backside.
On the same night, there were shameful scenes at Vale Park after Port Vale beat Swindon Town. Vale fans invaded the pitch and footage showed punches thrown at players.
Nottingham Forest thug Robert Biggs, 30, was this week jailed for 24 weeks for head-butting Sheffield United player Billy Sharp during a pitch invasion on May 17.
Now club bosses, the FA and the police are scrambling to find a solution to stop pitch invasions.
Liverpool boss Jurgen Klopp said they were "dangerous" for opposition players. He said: "We can celebrate without threatening ourselves and the opponent."
Newcastle manager Eddie Howe said: "I don't mind the celebration aspect. It's the aggression towards the opposition, it's swarms of people around one or two people. That's something we have to act very quickly on because we want to avert potential tragedy."
Norwich boss Dean Smith said: "I don't think security-wise we're doing enough. Football fans, we missed them during the Covid period.
"But come on, give your heads a wobble, you don't want to be running on and attacking people and managers. It's a major concern."
Commenting on Thursday's violence, Swindon Town boss Ben Garner said: "I don't know where we're going to as a country, but it's absolutely disgusting."
Swindon forward Harry McKirdy said: "Bottles, coins, lighters thrown [at] me, running on and hitting and kicking me/team-mates. Too far." Police have ruled out a return of fencing, which was scrapped in the wake of the Hillsborough disaster in April 1989.
But club bosses say something must be done. Accrington Town chairman Andy Holt said: "What do we do? We know full well fixed physical barriers can end in awful disaster. It's unreasonable to expect decent stewards to hold back 100s."
Head of football policing Chief Constable Mark Roberts said: "There needs to be a deterrent, that people face a sanction. We need to do something to address the behaviour, because once people are on the pitch it is then impossible to safeguard the players."
He suggested clubs might have to invest in mechanisms like those at Wembley which can be collapsed in an emergency.
The FA said the invasions "simply cannot continue" and announced a review of regulations to "stamp this behaviour out". In a statement it said: "Clubs play a vital role in addressing this issue, and they need to prevent pitch invasions from occurring, as well as taking their own action against those that break the rules and the law."