Investigations have begun into "large-scale trouble" at West Ham's Upton Park ground during a match against Millwall.
Fans who were at the game have been contacting the BBC. Here is a selection of their experiences.
DANIEL, ESSEX, SPECTATOR
"I don't support either side but was there with friends who are Hammers supporters.
Seeing the violence outside the stadium was something I can't really put into words to describe.
Daniel from Essex reckons some fans were up for a fight no matter what
We didn't feel safe, obviously, but also it was just scary to see how up people were for a fight.
We walked past a pub on the way to the ground, even before the match had started and heard chants of 'we hate Millwall! We hate Millwall!'
I also wonder how many people there were genuine fans because I saw many people in old shirts - surely if they were fans they would at least be wearing replicas that weren't years old?
Above all though, the police were brilliant. In the ground, after the scuffle following the first goal, I thought they did an amazing job of not making things worse. They deserve praise.
Mostly though, being there last night is an experience I will never forget. But for all the wrong reasons."
JIM WHITING, WEST HAM FAN
"I am a West Ham season ticket holder and have been going to games since the 1960s. This is the worse violence that I have seen for a long time.
I would describe the events outside as hooliganism and those inside as just stupidity.
Before kick off, there were a lot of Millwall "fans" blocking Green Street which leads up to the stadium. They were throwing things at the police and West Ham fans. The police managed to coral them away and re-open the way to the ground.
During the match, there were three mini pitch invasions, mainly by silly youngsters who thought it was funny to run on the pitch. The vast majority of them were youths.
I don't believe that any of the trouble outside the ground was caused by real fans of either club. This appeared to me to be a good excuse for a bunch of idiotic thugs to act in a violent way.
The vast majority of the 24,000 crowd watching the game were there only to do exactly that, as they were real fans."
HARRY HILLMAN, WEST HAM FAN
"As we came towards West Ham on the underground, we realised Upton Park was shut and I started to worry. As we got closer to the stadium, things got worse.
Walking up Priory Road behind the stadium we could see a large group of Millwall fans apparently looking to cause trouble. I covered up any West Ham badges I had.
I was shaking a little. I was more worried about my mum and dad who were with me.
At the match there seemed to be only a small number of stewards around the Bobby Moore stand. So when the pitch invasions started they were powerless to stop them.
As we walked out of the stadium, there were many West Ham fans walking towards the away exits. Unfortunately many were bragging about starting fights with Millwall fans.
Some were talking about stamping on fans' faces. I think that the police were unprepared for the level of violence that transpired during and after the game."
Hundreds of you have been e-mailing the BBC with your thoughts of the violence. Here are some of the comments you've sent to us.
As I'm sure most football fans out there would agree that those involved in the violence are a disgrace and should be ashamed of themselves, the sad thing is they're probably patting themselves on the back and will be congratulating themselves for a long time to come. How can you tackle that? (forgive the pun...) Richard, Salisbury, UK
This must be stop dead now before other people copy it and we are back to the 1970s. Punish the clubs by declaring their results void, banning them from playing for the rest of the season and relegation. That would shock football to the core and stop this happening ever again. Dave, UK
I hope the police hunt down every single one from the video footage and embarrass them in front of friends, family and employers, before prosecuting them.
At rugby and cricket you sit alongside opposition fans, the bars are open and you all have a thoroughly good time. How sad football has become. Fi, Gloucestershire, UK
Craig says that he's been attending matches at West Ham for more than 18 years and nothing was an intense as Tuesday night.
Just imagine if you had a brought your children out to see a match and that happens, how on earth would you explain what was happening? It's just like watching a pack of animals, a disgrace to this country. Mark, Cheltenham, Gloucestershire
After the disgraceful display last night, FIFA have every right to say NO to England hosting the 2018 World Cup. Again the minority spoiled it for the rest of us. Chris, Barnlsey, South Yorkshire
I think that West Ham and Millwall should both be deducted 30pts in their respective leagues, there is absolutely no place this in football. Pete, London
After last nights utterly disgraceful and despicable hooligan behaviour, I think both teams should be removed from the Carling Cup campaign altogether.
These hooligans are not even football fans, they are calculating thugs just out to call violence, vandalism and out to hurt innocent people and victims. Paul, Telford, Shropshire
Amateur footage of unruly football fans at Upton Park
Bang goes our chances of hosting the World Cup with these scenes, the fact that the riots were planned makes it even worse. The recession has taken us back to the 80s and now it looks like football is following. I am disgusted Laura, Bristol
I work at Canary Wharf and boarded the tube at 6.30 towards West Ham. I was scared in the carriage as the fans were shouting, chanting and banging the walls and the doors of the train. Their behaviour and language was disgusting. I have never felt so ashamed to be British. Pennie, London
I think we have to be careful not blow this out of proportion. It is hopefully a one off between two clubs who have a history of rivalry. It is despicable that a small group of people are set on causing trouble and it has the potential to ruin the game for the majority. JJ, Luton, Beds
Anybody who thought football violence had gone away, guess what? The scenes last night are repeated around the grounds on a smaller scale every week. That is why I rarely go to live football matches. I have never seen any violence at any of the Rugby Union / League or Ice Hockey games I go to and those sports are much more physical, but fans appreciate the commitment and skill, from whichever side shows it. Greg, Cardiff, Wales
I attended the game last night. The majority of the violence came from ticket-less "fans" outside the stadium. Inside, there were around 50-100 fans who invaded the pitch to celebrate...who were booed by the remaining 25k fans.
As well as this, there was pushing & shoving in one corner of the stadium between fans, police & stewards.
I'm not condoning any of the violence, and my thoughts are with the stab victim & his family, but I have not witnessed in any report a comment referring to the fact that the majority of people at the game were well behaved, proper fans.
If even 1,000 people were involved in the violence (which I doubt) this still only accounts a max of 4% of the people there last night. Lee, London, UK
Last night's trouble will probably affect England's chances of hosting tournaments, but it shouldn't do. The violence associated with football is far greater in many other nations across the world. Unfortunately the trouble will fuel William Gaillard and UEFA's anti-English rhetoric. Dom, London
West Ham and Millwall should both have some of their league matches played behind closed doors. This is justified punishment I feel for the incidents of last night. This kind of thing should be stamped out and the FA and police are going to have to work harder to eradicate the mindless morons who call themselves football fans. James, Shrewsbury
The solutions are simple. Both clubs should be kicked out of the Carling Cup immediately with no recourse to appeal. Any troublemakers identified should be prosecuted and receive lifetime bans from all football matches. The man seen dancing on the pitch with a toddler on his shoulders should also be identified as a matter of urgency and reported to social services. Simon, Shrewsbury, England
I wasn't at the match but I experienced the beginnings of this clearly pre meditated violence on the Tube on my way home from work on the Jubilee line at around 6.45pm.
It started as a normal tube journey until large numbers of vociferous Millwall fans crowded onto the train, easily 50 in my carriage alone.
Chants of "we hate West Ham, nobody likes us we don't care", initially light hearted became more and more strident and soon degenerated into racial chants accompanied by thumping on the ceiling of the carriage, denting it in several places, jumping up and down in unison swaying the whole carriage.
The whole atmosphere became more and more threatening as they psyched themselves up and began ripping up seats and attempting (unsuccessfully) to smash the windows with them. Jim, Hornchurch, England
The scenes at West Ham, although disgusting, are nothing compared to how football used to be in England. Also, the scenes of last night are nothing compared to violence in Italy or South America, for example, where leagues and games have been suspended.
Fans can't even go to Rome due to the violence and stabbings - imagine if English football was so bad that visiting fans could not come to London? Andrew Hunt, London
Matt, who sent this photo, reckons that the police should be complimented for handling a tense situation inside the stadium.
I'm a West Ham fan and am very scared at the prospect of what may happen to us here. For those inside the ground they should be banned for life and prosecuted if possible.
For those outside the ground I hope they find them and can identify whether they are even football fans or whether it is just an excuse for organised violence under the guise of football - I question this as I believe there was fighting still taking place in the streets even when the game was on - so it seems these animals are more concerned with violence than the game of football. Jo, Slough
I am a West Ham fan, and I understand the rivalry between us and Millwall. But last night? That is too far. It spoiled what was otherwise a good win, and a competitive game of football. Both sets of fans should be ashamed. Credit to the stewards at the match, they did the very best they could with both teams supporters. James, Walthamstow, London, UK
I, a Millwall fan, was at the game last night and was not entirely shocked at the situation.
Suggestions of organised clashes are vastly exaggerated, it was obvious that a few hundred West Ham fans would wait outside Upton Park Station at 7pm for the Millwall fans, I wouldn't deem that organised clashes though.
Very little effort was made by police or stewards to help guide Millwall fans to the away end, we were told to walk all the way round the ground as they wouldn't open the adjacent fence.
Those who were pointed down Priory Road were met by an angry mob of West Ham fans which resulted in the stabbing.
More effort should have been made by police to get West Ham fans inside the ground rather than let them wait around outside Upton Park Station for the Millwall fans. The crowds didn't clear until about halfway through the first half causing real fans to miss the start of the game. Matty, Chester
Were you at the game or in the area? What can be done to stop the violence being repeated? Send us your comments using the post form below.
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