Bang, Bang...

Latest Grey's Anatomy season finale scoop from TV Guide:

Be on the lookout for an armed man on the loose in the halls of Seattle Grace.

A source confirms that the top-secret story line of Grey's Anatomy's season finale is a gunman who terrorizes the hospital. So who's the shooter? We hear that both the shooter and his victims will all be familiar faces to fans of the show.

In fact, the source goes on to say that the victims won't just be the random candy striper or nurse from down the hall, meaning you may want to keep the Kleenex handy. No one is safe.