If this is a terrorist would it be more effective doing a single shot and fleeing...or opening fire on a group of people then fleeing....I would think they would go for the larger group instilling more terror....
You'd sure think so, wouldn't you?
As I have pointed out in other threads, it is far easier to get away after a single shot than standing on a hilltop spraying bullets. It is very difficult to determine the direction of a single shot since your brain is not in the "where is that coming from" mode. If your whereabouts are not detected immediately, nobody sees you quietly leaving. This technique has been used by poachers and snipers for a long time.
It is also notworthy that many of the hijackers did not know they were on a suicide mission. In spite of hype to the contrary, it really is difficult to find someone (especially in America) willing to martyr themselves.