The attacks on Paris

At last, as some predicted the struggle with the Islamic extremists ISIS has come into the heart of Europe. Multiple attacks from heavily armed gunmen shot and killed many Parisians this evening out for an evenings entertainment on the streets of Paris.

One of the frightening aspect of this event is the apparent inability of the police and security forces to contain and apprehend any of the attackers so dispersed was the attack. Clearly well planned, involving people who are fanatical and willing to die for their cause it opens up in Europe a Pandora's box. 

Is this the start of a wholesale conflict including other major cities or is it a one off, a reprisal against France for agreeing to bomb Syria.
Does this sort of well armed attack mean that Europe and ourselves in the UK will need to bring in all sorts of security measures that will not only make our lives more difficult but also cross the line of what we believed was the demarcation on security surveillance and information gathering.
And finally will it begin to ask the question. Is the invasion of Europe by immigrants, in some cases fleeing for their lives in others seeking economic betterment, young men from the area where ISIS have a stronghold, Syria, can this be allowed to continue since it is assumed that infiltrated amongst the genuine asylum seekers are many Jihadis intent on setting up cells throughout Europe to wreck havoc at a later date.
Is it not time for the humanitarian emotions to be reigned in and face up to the threat with a stringent response to an emergency set of circumstances, a sort of martial law where prima facie evidence is not required to arrest known activists.
When the game changes the rule book becomes redundant and new rules apply to meet the needs of the new situation ?