Here the ISM claims the Israeli navy rammed a Palestinian fishing vessel.
The ISM claims the navy yelled over a megaphone, "When the internationals leave Gaza, you will all be made to pay."
UPDATE: from an ISM press release, Sept. 16:
An Italian solidarity activist who sailed into Gaza has been injured today by the Israeli Navy while he was accompanying fishermen in Gaza.
Vittorio Arrigoni was hit by flying glass as the Israeli navy used a high power water cannon against the unarmed boats. The water canon smashed the glass surrounding the steering section of the boat, with shards lacerating Vittorio's back. He was been taken to hospital immediately upon reaching shore, requiring stitches.