I am alarmed but not entirely surprised as parties like this have been gaining ground in many countries.
The question the main parties Left, centrist and Right must ask is what is they are doing, or not, that is pushing so many of their usual supporters into the arms of these extreme ones. That will vary from country to country, as will the L-R spectrum if such a subjective thing can be compared.
Back in the 1960s, most of the extremist fringe was hard-Left, even Communist. Now it is hard-Right, but it may lead to something of a reaction encouraging the hard-Left.