Viewer discretion advised.

You don't often hear those three words at the end of a promo for Grey's Anatomy, but for next week's season finale, ABC feels they apply - and probably for good reason.

A crazed gunman on the loose will do that.

Divided into two episodes - "Sanctuary" and "Death and All His Friends" - the two-hour finale certainly does qualify as a game-changer. Here's the first promo for it ...

[video url="http://www.tvfanatic.com/videos/sanctuary-promo/" title="Sanctuary Promo"] [/video]

Wow. Seattle Grace is a "Sanctuary" no more. The scene in which Bailey watches the pair of feet walk ominously toward her, then appears to be dragged away? Not un-intense.

But who is the shooter?

Follow the link for our photo gallery from the Grey's Anatomy finale, then check out another, possibly even more chilling promo for the season-ending event after the jump:

[video url="http://www.tvfanatic.com/videos/death-and-all-his-friends-promo/" title="Death and All His Friends Promo"] [/video]

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.