Up to 100 people have been involved in a brawl at The Windmill pub in Waterloo on Thursday evening.
One person is believed to have been seriously injured in the incident in The Cut. The brawl occured just after 5pm. As police approached from the Waterloo end of The Cut, the fighters dispersed towards the Blackfriars Road end.
A BBC London reporter at the scene said that every window at the pub had been broken, and bins had been thrown through the windows.
The fight is understood to have involved Millwall and Portsmouth fans, whose teams are playing at the New Den tonight.
There is a heightened police presence in the area tonight, with officers posted at other popular Waterloo pubs including The Wellington. Armed response units were sent to protect Portsmouth fans drinking at the Fire Station bar.