Its a sign that  unrestrained multi culterism and diversity by immigration is not necessarily beneficial .

At some point, if the inflow is seen to be destabilizing, the established culture will react and that reaction could be violent.
This sensitivity is heightened when the invading culture has quite different views on  human rights and liberties that the existing culture accepts as sacred.

Consider the millions of illegal mexican immigrants and  illegals in the US.
Not a single case of terrorist slaughter of Americans.
Their cultures are very similar.

Consider islam ,with its tenets that as implemented by ISIS that all infidels must be killed, if they cannot be converted.
Consider sharia law and women as chattels .

These are quite different cultures which inculcate fear and loathing by the existing culture.
Hence that populist movements  that we see in Europe and the US and also here in Canada.

History shows that it is to be expected