The shocking Grey's Anatomy promos (bullets flying, blood spilling) and revealing previews (pregnancy tests and important guest stars) have already given us a lot to think about.

The additional clips below from this week's two-hour finale offer more insight into the "game-changing" season-ending episode as we fill in the blanks prior to Thursday night.

As we know, there is a shooter loose in the hospital. Here's the moment in which Derek first realizes it, immediately protecting Meredith and Cristina before venturing back out ...

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Could Derek have put himself in danger in order to protect his wife and her best friend? That would be a pretty McDreamy thing to do. But is it the acting Chief who gets shot?

We'll have to wait and see (and debate that endlessly, as well as the identity of the shooter). For now, here's another clip of a surgery scene featuring Owen, Cristina and Teddy.

In the midst of it, Cristina asks Owen point blank who he loves ...

[video url="http://www.tvfanatic.com/videos/greys-anatomy-season-6-finale-sneak-preview-4/" title="Grey's Anatomy Season 6 Finale Sneak Preview #4"] [/video]

UPDATE: Three more clips now added (apologies for volume) ...

[video url="http://www.tvfanatic.com/videos/greys-anatomy-season-6-finale-sneak-preview-5/" title="Grey's Anatomy Season 6 Finale Sneak Preview #5"] [/video]

[video url="http://www.tvfanatic.com/videos/greys-anatomy-season-6-finale-sneak-preview-6/" title="Grey's Anatomy Season 6 Finale Sneak Preview #6"] [/video]

[video url="http://www.tvfanatic.com/videos/greys-anatomy-season-6-finale-sneak-preview-7/" title="Grey's Anatomy Season 6 Finale Sneak Preview #7"] [/video]

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