Watch Everton and Millwall supporters clash outside The Den ahead of FA Cup tie

The Met Police have appealed for witnesses after a man was slashed in the face

Everton and Millwall fans clashed outside The Den in a mass brawl on Saturday afternoon ahead of their fourth round FA Cup tie. The Metropolitan Police have appealed for witnesses after a man was slashed in the face during the fracas. Police had to separate large groups of supporters outside Surrey Quays station, not far from Millwall's stadium. https://twitter.com/danilob4167559c/status/1089210770125176838?s=21 The incident appears to have taken place near a block of flats on Hawkstone Road, South West London, one of the roads leading from the tube to the stadium. Officers arrived on horseback to divide the two groups, as punches were thrown and the violence intensified. Millwall fans also surrounded the Everton supporters' bus as it arrived at the ground, intimidating the travelling fans. https://www.instagram.com/p/BtGw8tgh-CD/?utm_source=ig_embed&utm_campaign=embed_loading_state_camera Footage from inside the supporters' bus also emerged on social media, showing broken windows. Warning: severely bad language. https://twitter.com/United_Webby/status/1089237078012055553 A Metropolitan Police spokesperson said: "At around 16:42hrs officers became aware of a large group of males fighting in the Hawkstone Road area. "One male aged in his 20s was discovered suffering from a slash wound to the face. He was taken by LAS to a south London hospital. His injuries are not life-threatening. "A crime scene remains in place. Officers worked to separate the groups with support from the Mounted Branch. At this early stage, there have been no arrests." Detective Inspector Darren Young, of the South Central Command Unit, said: “The behaviour of those involved in this incident is nothing short of disgraceful and those involved can be certain we will be working to identify them. “We are aware of the video circulating online, which has quite rightly elicited shock and disgust. We are looking at it and urge anyone with information that could assist police to call 101 referring CAD 5117/26 Jan.” Millwall won the game 3-2 thanks to a late goal from Murray Wallace.