I don't understand how a someone would kill on behalf of religion mostly soo smebody practicing a foreign faith!

They are brainwashed by their leaders interpretation of the Quran.
Many Human beings are irrational by nature , especially the youth and it is easy to turn them into fanatics by playing with their emotions.
Some are so miserable on earth that they seek what they think is a first class ticket to heaven by killing innocents. They have been brainwashed into thinking that their life in heaven will be better than the poverty they experience on earth.

And they were living in a 'secure' estate just outside a military camp. We have lost it. What is the purpose of camp there if we cannot engage these mindless external aggressors?

ION, I sincerely pray for the nyeri man. You stay at home, your wife wants to chop your transformer, you go outside the ugus want your life.

http://www.nation.co.ke/...183298-3428816-klap1lz/

12 killed in Mandera overnight attack by Shabaab gunmen - VIDEO

I don't know whether to direct my pain to alshabab or the govt?

Ask yourself: how can alkefafu all the way frm Som. precisely know which very specific place (Bishar Guest Hse) has visiting non-locals at a very specific time?
Clearly, the visiting artistes were sold out.
Someone in Mandera had very good timely, accurate and actionable intel for the unwelcome guests from Som.
Meaning, logically and by simple deduction therefore, that there are very many alkefafu spies and sympathizers in Mandera.
That is where the weeding has to start - alkefafu frm within.

Issue no.2 : But why cant the local Muslim communities weed out these sympathizers/ spies and expose them?

@swenani you are a well traveled man no doubt,shida za hii inchi ni serikali!

According to Wikipedia, it's something to do with allegiance to some other human, sad.