I saw it in the news as well, though I've heard that the reason the Israelis stormed it is they requested the ship dock to let them inspect their cargo before transporting it to Gaza (to make sure there weren't any weapons) and they refused to do so. Then they attacked the Israelis when they boarded the ship.

Not that it justifies the deaths, really, but I've heard there were other aid ships that got to Gaza without any trouble because they were OK letting the Israelis see their cargo...