It is believed the violence flared between the rival supporters after an argument over who would be the first to grow opposable thumbs.
West Ham fan, Wayne Hayes, said: "They was sayin' that one of 'em already 'ad fums and could use tools and evryfin'.
"And I was like, 'you fackin' bastards, my old dad nearly 'ad fums once, you callin' me a cant?'."