Erik Kripke, the creator of Supernatural, has released this statement:

Everyone at ‘Supernatural’ is walking around in a daze, shocked and absolutely devastated. Kim was a brilliant director; more than that, he was a mentor and friend. He was one of the patriarchs of the family, and we miss him desperately. He gave so much to ‘Supernatural,’ and everything we do on the show, now and forever, is in memory of him.

I’m sure he will be missed by many fans, myself included.