Police have arrested 14 people after violence broke out among Millwall fans during the FA Cup semi-final against Wigan.
Sources have told Sky that Millwall are investigating the possibility the fighting could have been triggered by a dispute between two families within the crowd.
During the second half of their 2-0 loss to Wigan on Saturday, around 20 Millwall fans were involved in a clash behind the goal at Wembley Stadium.
The disturbing scenes, which were witnessed by millions on television, left some fans bloodied and youngsters in tears.
A Scotland Yard spokesman said 12 of those held were Millwall supporters and two Wigan fans.
“Investigations into the circumstances of the incidents are continuing,” he said.
Four of the arrests were for affray, one for affray and possession of Class A drugs, one for affray and assault on police, two for public order offences and one for assault causing actual bodily harm and possession of Class A drugs.
One was for a racially aggravated public order offence, one for ticket touting, one for possession of Class A drugs, one for theft and possession of offensive weapon, and one for breach of banning order.
Four officers received minor injuries in the trouble.
Alex Horne, general secretary of the FA, said: “The Metropolitan Police and the FA are investigating scenes of sporadic violence and disorder in the Millwall FC
“The FA and Wembley Stadium will work with police and representatives of Millwall FC to review all events.
“We will look to ensure those involved are identified and we would call for criminal charges and a football banning order to be brought against them.
“The FA deplores the scenes which have taken place, which are unacceptable. Everything will be done to take action against those involved.”
Millwall have long had an unwanted reputation for hooliganism and Saturday’s scenes were a throwback to the 1980s.
The club’s chief executive Andy Ambler said it would do all it could to find those responsible.
“Our position is clear. Anyone associated with our club found guilty of violent behaviour will be banned indefinitely from Millwall matches in addition to any punishment they receive from the authorities,” he said.
“Having worked so hard to show the positive side of our club both on and off the field, we cannot allow the actions of a mindless minority to undermine that.
“At this stage we are still in the process of establishing the full details of what happened in a section of the ground during the second half.
“When we have those facts at our disposal and the police have completed their investigations we may be in a position to comment further.”
Millwall chairman John Berylson, who flew in from the United