Millwall took the spoils of this fierce London derby -but both sets of fans disgraced themselves.
A total of eight mounted Police and three-dozen riot Police were brought on to the pitch to stop away fans from invading the playing area as West Ham fell apart.
While The Den has reputation as a hotbed for violence, this time the West Ham fans were in the dock as 250 supporters tried to force themselves onto the pitch.
The match ended with three away fans thrown out and two arrested for criminal damage after they trashed the toilets in The Den. Police are still searching for two more.
While there were no Millwall fans involved in thescuffles in the stands, they also had one supporter arrested for racial abuse, and four were thrown out of the stadium.
Things boiled over on the hour with the Hammers 3-1 down following West Ham goalkeeper Stephen Bywater's sending off for felling Neil Harris in the box.
A band of away fans ripped up barricades - including a massive anti-racism banner - as they tried to force their way to the Millwall sections of the stadium.
West Ham boss Alan Pardew shouldered the blame for the crowd trouble and said: "You can't condone that sort of behaviour.
"But by the same token, the way things were going on the pitch were always going to make our fans edgy. We have to take responsibility for that." Things went downhill for West Ham in the 34th minute when Christian Dailly tapped Paul Ifill's cross past his own keeper.
The goal came after the visitors had a huge let-off when Neil Harris squandered a penalty - the first of two missed by the Lions in the game.
Tim Cahill made it two just after the break but Marlon Harewood put the Hammers back in contention two minutes later with a penalty after Matt Lawrence handled in the area.
Cahill bagged his second with a sweet volley from ten yards before Bywater was handed his marching orders.
The Aussie midfielder blasted wide of the post to deny himself his first-ever hat trick as things were getting ugly at the other end, before sub Nick Chadwick netted ten minutes from time to seal it.