Communist groups have made a habit recently of violently attacking anti-Islamic protesters. IMHO, this should have been stopped by police long ago. It wasn’t, and now the anti-Islamic groups have no option but to defend themselves.
Police are now complaining about the violence, but its only happening because they failed to stop it when the communists first resorted to it.
The violence is a shame, but in fact the anti-Islamic protesters have a right to express their views and a right to protect themselves.
There would be no violence if the communist groups stayed away.
If a permit was issued for the protest, then it should be clear to the Police exactly which group is to blame for the violence.