The civilians being shot by IDF soldiers however is not hearsay at this point, it has been confirmed by the Israeli government, it was hard not to in the face of the footage from the Turkish crew that made it past the black-out.
Interesting tidbit: AlJazeera says "Israel 'attacks' Gaza aid..." with "attacks" between quotes while Haaretz says "At least 10 activists killed as Israel Navy opens fire on Gaza aid flotilla"
And BBC says they did not turn back "to avoid a confrontation" they turned back to make sure the confrontation would be during daylight so they could get the most publicity from it.
1. End or renegotiate the blockade.
2. Prevent the ships from running the blockade.
They chose to do #2, which isn't particularly surprising. Letting ships run the blockade for any reason effectively ends the blockade.
This doesn't get into rightness or wrongness of the matter, but the Israelis are very tough people and a little less concerned about newspapers than most developed countries. I have to think the organizers knew this was the inevitable outcome, and that they must be trying to get sanctions, reprimands, or otherwise lower Israel's international standing. And again, not looking at rightness/wrongness, it seems to be working.
This seems to be a major focus of modern warfare and strategy - Israel has overwhelming military superiority, so its opponents only have two options - asymmetrical warfare ("terrorism", I hesitate to use the word because of how often it gets thrown around) and this sort of international public relations, which is proving remarkably more effective than anyone could have imagined 100 years ago.