British Transport Police detectives are appealing for witnesses after an early morning fight on the steps outside Waterloo station left two men hospitalised.
Investigators want to hear from anyone with information about the incident which took place at about 4.45am on Sunday 23 January.
BTP officers were called to the Victory Arch after reports of two groups of men fighting.
While both groups waited for the station to open, heated words were exchanged and the situation escalated into a fight.
Officers attended and arrested six men, aged between 17 and 25, for violent disorder.
The men, from Hendon, Bushey and Rickmansworth, have since been released on police bail, pending further enquiries, and will return on Monday 7 and Tuesday 8 March 2011.
Five men aged between 20 and 40, all from Bracknell, Berkshire, were attacked. Two required hospital treatment as a result, although they were later discharged.
"We are currently making local enquiries, including looking at what took place before, during and immediately after the fight," says Detective Sergeant Pete Thrush.
"It's important that we build up a clear picture of events and we believe this incident may have been witnessed by a number of people who were at the Victory Arch steps at the time.
"If you were at the station and saw what happened, we want to hear from you."
Anyone with information about the incident should contact BTP on Freefone 0800 40 50 40 quoting reference B5 of 26/01/11.