Militants would not know when the bus would arrive and through what territory and who was in the bus. This was a planned attack by a foreign intelligence agency.
you just invited the flame war
ok let me educate you on the bold part. its not the first attack. these attacks have been happening since the good old times when the victims of terror were only shias, we normally remember those times as golden times,
the people of Kohistan are heavily influenced by Deobandi school of thought and are the deadly against the Shias. during the Zia era they even launched an all out war on northern areas which has a sizable shia population. there were thousands of deaths and destruction of property.
since the only electronic media channels were government controlled and the print media could only print what Government allowed so most of us dont even know what went on there during 88-89.
The Koshistani fanatics also form the front troops of the taliban. they have a very simple method of checking the shia.
they know that any vehicle with NA registration or a public transport going there will defiantly have shia.
just like the Baloch terrorists stop the buses coming from Sindh to Balochistan.
then they march out people and check their ID cards and then shoot them on site without discriminating between women, men, children old or young. you dont relaly need a high tech system or intel for that. simple rule of thumb that if a place has a majority of a certain ethnicity or faith, then any transport going to and from will have people of that community.
they use the same principle on the vehicles going to Parachinar. and its bad enough if you are bringing food to the shia besieged town, it wont matter if you are a Sunni. your crime is so big that you will be burnt alive with the truck. thats what happened two years ago to trukers who were stopped by taliban and burnt along with the food supplies.
this is why our country is being given the Drone therapy. its a shame that drones are killing civilians too. but rest assured. these drones are the answer to the calls of the weak members of the community who are suffering at the hands these terrorists who share the Al Qaeda ideology and have the sympathies of the saudis.
give it few days. all will be forgotten about this and we will move on. these terrorist know it too.