Weekend pitch invasions in England and Scotland have raised fears for player safety with those in the game warning of potential tragedy unless firm action was taken to tackle the problem and the governing FA saying a line had been crossed.
Professional Footballers' Association (PFA) chief executive Gordon Taylor said there was real concern after 'cowardly and criminal' attacks on players by spectators running onto the field of play.
Aston Villa's Jack Grealish was punched in the face by a man in a Championship (second tier) game at local rivals Birmingham City while Manchester United defender Chris Smalling was shoved at Arsenal.
In Scotland, Rangers captain James Tavernier was attacked at Hibernian.
Individuals have been charged in relation to all three incidents.
"We have seen an increase in such behaviour at clubs this season. It's been racist abuse, anti-Semitism and now its real fear for the safety of players," Taylor told Sky Sports News television.
"We have been warned now on too many occasions. This has got to be dealt with by the football bodies, the police, the stewards and the clubs. There is a total responsibility."
"We have got to address it now. If not, it is going to be too late and there is going to be a tragedy."
The English Football Association condemned Sunday's incidents as entirely unacceptable.
"We will be working with the clubs, the leagues and the police to discuss what collectively needs to be done to protect players and officials on the pitch," it added.
The FA said it had also written to Birmingham City and Arsenal for their observations and details of the security measures they had in place.
Sports Minister Mims Davies had earlier called on the football authorities and clubs to take strong action.
"Protecting players' safety is of paramount importance and every possible step must be taken to ensure that they are not put at risk," she added in a statement.
Taylor mentioned a range of possible options, including fines, points deductions and playing behind closed doors and said spectators also needed to be educated about the consequences of their behaviour.
Rangers' manager, and former England captain, Steven Gerrard said there was 'huge concern' and agreed fans had to play their part.
"Fans have to take responsibility and think before they do these type of things, because if it continues someone is going to get hurt and hurt badly, and no-one wants it to get to that stage," he told reporters.
With rising knife crime and deaths from stabbings in the headlines, former England striker Alan Shearer feared an escalation.
"If we don't stamp it out now, next time it could be a knife," he warned in the Sun newspaper.
"It's that serious. Where are we at in football when some thug thinks that is what he is going to do? The football authorities have to be seen to nail Birmingham for the behaviour of their fan," he added.
Other cautioned that points deductions imposed on clubs for the behaviour of their fans could encourage others to fake allegiance in order to sabotage a rival side.
Fences were common at English grounds in the 1970s and 1980s in response to an epidemic of pitch invasions but were removed after 96 fans were crushed to death in the 1989 Hillsborough stadium disaster.
