There is an important facet of the events of last night that has not been emphasized.
The IDF soldiers went on board the ship with the expectation that they would be met with "non-violent resistance." The reason that they had those expectations was because the flotilla organizers made very clear that this is what they planned to do - as they said, "The only resistance that there might be would be passive resistance such as physically blocking the steering room, or blocking the engine room downstairs, so that they couldn't get taken over. But that was just symbolic resistance."
Because the IDF foolishly believed them, they dropped onto the Turkish ship armed with just riot-dispersal paint guns, plus personal handguns as a last resort.
And they fell into a well-planned ambush.
It is still unclear how many people were killed - the initial reports of 16 seem to have exaggerated, another likely Free Gaza lie - but the IDF had zero interest in killing anybody. The IDF only opened fire after first suffering from merciless, life threatening beatings and asking permission from their commanders.
At least some of the flotilla organizers, on the other hand, made clear that they wanted to become "martyrs."
The bottom line is, if the IDF had known that they were meeting with a mob of violent, crazy, suicidal Islamists, they would have prepared better for it and there would have been less loss of life. But since the Free Gaza and other sponsors of the ships made very public statements about their "peaceful" intentions, the IDF was ill-prepared for the confrontation and things went awry.
I do not know if Free Gaza knew that the Turkish Islamist ship would do what it did. Clearly they are supporting the violence after the fact. However, the FG mission was never a peace mission and was never an aid mission - it was meant to grab headlines, nothing more. The Turkish IHH mission, on the other hand, was military.