In extreme cases, police and bystanders have been killed, and body-armored riot police have intervened with tear gas, police dogs. There are, however significant cross national similarities in the ‘stage of development’ of the problem. Most countries experience an initial stage of sporadic violence directed mainly at referees and players, followed by a second stage involving violence between opposing groups of fans and against police inside the stadium and third stage involving an increase in violent encounters between these groups outside the stadium.
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