Crowd trouble at the Euro 2020 final at Wembley could have led to tragedy if England had won the game, the stark findings of an independent review suggested on Friday.
A 128-page report into the chaos at the showpiece game on July 11 concluded there were real fears thousands of ticketless fans could have stormed the ground had England beaten Italy.
The author of the study called it a "near miss" that could have led to deaths or serious injury, blaming it on a reckless "horde" of 6,000 or more fans without tickets.
"The drunkenness, drug-taking, irresponsibility, criminality, and abuse of innocent people... was shocking and intolerable," wrote Louise Casey.
"I am clear that we were close to fatalities and/or life-changing injuries for some, potentially many, in attendance," she added, calling the trouble a "national shame".
England's Football Association governing body, which commissioned the study, apologized and said it accepted its conclusions in full.
As a punishment, UEFA has banned supporters from England's next home international in their competitions.
Casey, a member of Britain's upper chamber of parliament the House of Lords, said much of the trouble was foreseeable and organizers had been caught off-guard.
There had been a collective failure to plan for the worst, and police were deployed too late.
She recommended the government consider the creation of a special category of matches of national significance, where security would be tighter and with curbs on alcohol.
Better stewarding in the area immediately around the stadium was needed, and harsher penalties for anyone involved in football-related disorder, she added.
The Metropolitan Police said in a statement that officers and stewards faced "unprecedented challenges and unacceptable levels of violence in trying to bring about order".
"We welcome the praise by Baroness Casey on the bravery of officers in directly confronting scenes of disorder," Metropolitan Police Commander Rachel Williams said.
"Her comments set out the unprecedented pressure officers faced, they are a credit to policing...
"We regret that we were not able to do more to prevent those scenes from unfolding."
Some 2,000 ticketless fans were found to have gained access to the stadium in 17 separate breaches of disabled gates and emergency fire doors to the ground.
The breaches, which began from 90 minutes before kick-off and continued up to the penalty shoot-out, "jeopardized the lives of legitimate supporters and staff", said Casey.
One individual even impersonated a steward and hijacked a disabled child in a wheelchair, separating him from his father, as he tried to get in.
Only 400 people were ejected but about 6,000 others, who appeared to have little or no interest in the game, were feared to have been preparing to storm the stadium.
The report quoted one emergency services official as saying the consequences of an England win would have been "horrific" and led to a major incident in London.
"Thank God England lost," an official from the Sports Ground Safety Authority added.
"If they had won you would have to open the doors to let people out and the stadium would have been stormed."
FA chief executive Mark Bullingham said everyone at the organization was "appalled" by the disorder on what was England's biggest game since the 1966 World Cup final.
"No event is set up to deal with such disgraceful behavior from thousands of ticketless fans. Collectively we must never allow this to happen again," he added.
Despite the Euro final mayhem, the UK and Ireland are considering a bid to host the 2030 World Cup.
Casey said those plans should not be abandoned because the lessons learned meant Wembley would be a safer place in the future.
"Hindsight is one of the most amazing things that means that next time you plan for something you can learn from the previous experiences," she said.
"The lessons that are learned from that actually make London and the country a better place than probably anywhere else because we're never going to let this happen again."
Urging football authorities to make the final a catalyst for change, Casey added: "There's something here about our national game that seems to be the vehicle for thuggery, hooliganism, and racism.
"I would like to see 'Euro Sunday' as a turning point, that means were we ever to win the World Cup bid, we would absolutely never see sights like that again."
