French policemen work in the police perimeter set up at the bottom of a building where a man, suspected of slitting the throats of his father and brother, was arrested on March 17, 2017 in Paris' trendy 11th district. The sources, who asked not to be named because they were not authorised to speak publicly, said the reason for the attack was being investigated. / AFP PHOTO / PATRICK KOVARIK (Photo credit should read PATRICK KOVARIK/AFP/Getty Images)