From facebook:
Slayer is devastated to inform that their bandmate and brother, Jeff Hanneman, passed away at about 11AM this morning near his Southern California home. Hanneman was in an area hospital when he suffered liver failure. He is survived by his wife Kathy, his sister Kathy and his brothers Michael and Larry, and will be sorely missed.
Not following the recent Slayer drama, I had no idea that he was in bad health. Awful news. RIP