The Hammers defeated Rapid Vienna 2-0 on Thursday night to maintain their 100 per cent record in the competition, with goals from Declan Rice and Said Benrahma.
As West Ham were on course on claiming the nmaximum three points of the game, there were also a few unsavoury scenes in the stands.
The viloent began just after England international Declan Rice tapped the home side in front during the first half after an impressive move by David Moyes' team.
According to police officers who were present at the game, both fans exchanged bottles of urine as other reports on various news tabloids indicated different objects were also thrown.
Prior to kick-off, small signs of trouble were witnessed as missiles were thrown between the two sets of supporters during a pre-match light show.
Looking to storm the home end, the visiting supporters vaulted the front of the away end in the Sir Trevor Brooking Stand.
The drama in the stands calmed down for the remainder of the game as Rapid were denied a penalty by VAR before Algerian forward Said Benrahma sealed the victory for West Ham in second half injury time.
Following the the full time whistle, some supporters in the away end once again found a wave of aggression crashing over them, confronted police offers who moved into the crowd to calm things down while others were caught on camera appearing to throw punches at the police.
