I've mapped out the home provinces of each of the activists who were killed and placed a marker in each province's capital. The data are based on a Zaman article (Turkish English-language newspaper) that appeared last weekend.
Those who died appear to have been from all over Turkey. They may well have met up before and prepared/trained together in the months that preceded the flotilla, but they're not all from the same approximate area (other than most of them being from Anatolia). We probably cannot derive too much meaning from geographical plot, but it does help rule out the hypothesis that I had considered according which the people who attacked the soldiers were a bunch of young people from the same small town. TO the contrary, the median and mean age of those killed was about 31.
My assumption is that most of those killed were directly engaged in fighting with the soldiers, but it's possible that some people were in the wrong place at the wrong time. What's clear is that the actions of a small group of hot heads completely changed the mind state of the boarding party and increased the threat perception they had, compelling the soldiers to use lethal force.