Assistant Chief Constable of Greater Manchester Police, Justine Curran, described the fans as being "like a pack of baying wolves".

BBC: Man United parade off after riots

They have sub-zero temperatures to contend with, howling winds and snow, and the only source of meat on the horizon -- a pack of timber wolves -- has its own ideas about the pecking order on the food chain.

CNN: Review: 'The Grey' is a walk on the wild side

In 2006, a pack of six Mackenzie River wolves - a North American wolf - were put down because they were "not portraying their natural behaviour".

BBC: Pup and mother Elara