Three refugees were detained and five more treated in hospital after a vicious brawl broke out at a migrant center in the German city of Dortmund. Police have launched a criminal investigation but are still puzzled over the exact cause of the violence. Scenes similar to an all-out street fight first appeared in a video on Facebook, which was then shared on other social media platforms. The footage shows men and a woman punching and kicking one another. Some of those involved are seen in the footage smashing chairs over the backs of fellow migrants.Only eight refugees, aged between 14...