I don't even think they have said the man is innocent yet. Evidently, he was under police surveillance, and the cops claim to have found a weapon at the scene. Still, I think there are some underlying causes here too which while certainly do not excuse this behavior, go a long way to explaining why it occurs from time to time. These are mostly young people in immigrant neighborhoods, so it's no surprise that this stuff crops up during times of economic hardship, social cuts and anti-immigrant populist rhetoric.