this is going to keep happening and get worse in other parts of Europe if they don't man up and realize that Islam is the problem and that they should temporarily but completely and indefinitely ban all Muslims from immigrating to those countries. All Mosques should then be investigated thoroughly and if questionable, shut down. All questionable muslims who are not yet citizens should be deported immediately. It's time to get serious.
Other countries, the US in particular need to take notes and see what happens when immigrant Muslims become a significant part of your population.
For those who haven't, you need to read "Clash of Civilizations" by Samuel P. Huntington.