In 2009 filmaker Uwe Boll made 'Rampage' a film about a massacre by a lone gunman attired in Kevlar armour and police-style helmet. Below is the film poster.
A friend on mine , video game and non-Hollywood film fan, showed me part of the film.
The body armour and helmet of the blond protagonist reminded me of this photo - allegedly the police-uniform clad Anders Breivik sometime around the bomb-blast in Oslo but before the massacre on Utoya Island.
Uwe Boll's ending also raises questions about the suicide of shooters at the end of their mass-murdering [ unusually Breivik did not kill himself ]
Perhaps Breivik is one of the sanctioned 'shooters' whom his superiors allowed us to see , for fun. The other shooters were the 'police' who arrested him, in the same way as in some bank-heist hostage films, the robbers walk out with the hostages. There is the possibility the robber might get caught out by interrogation but who is going to question the police.