According to Italian police, who picked up the surviving (non-christian) migrants from a boat. I am sure it was only pure coindcidence that the non-christians murdered the christians and did not kill not adherents of their own religion. Couldn't have anything at all to do with their religion, of course, because it is a religion of such tolerance of others. Yeah - right.

http://www.cnn.com/2015/04/16/europe/italy-migrants-christians-thrown-overboard/