Meredith finds Cristina in a hallway, and they muse un-seriously about the lockdown. "It's probably just a drill," Cristina says, "or a psych patient got out. Or a baby went missing from the nursery." Okay, the sarcastic edge she just gave "nursery" tells me we've still got some of the old Cristina. "Or," she says cheerfully, "there's an axe murderer on the loose." Meredith smiles and says that would at least mean mucho surgeries. Because they're so dark and twisted, you guys! They LIKE carnage! Boy, I hope nothing happens to remind them of the gravity of the place where they live and work. Cristina then asks if Mere told Derek about the baby and/or if he wept "like a bitch-baby" when she did. Mere says she hasn't told him yet, because he was in a mood. She wants it to be special. "You find out in the ladies room squatting over a stick," Cristina says. "Why does he get special?" Mere feels like her head's gonna pop off if she doesn't tell him, so she decides to tell him right now. Cristina wants to be there to see the bitch-baby tears, so she's coming too. It's saying that she broke up with Owen that convinces Mere to let her come along. Aw.
Down in the waiting room, Lexie asks Mark to sign a chart for something, while Mark wants to make small talk about the lockdown and Alex and how much he misses her. Lexie would rather he just sign the chart. A nurse yells at an unseen man that nobody's allowed to leave the floor. The man, Clark, turns around and fires two shots into her, and the room explodes into screaming and chaos. Mark hauls Lexie to the ground with him. They crawl over to Nurse Vivian, who is totally dead, and Mark picks Lexie up and bolts for the nearest elevator. When it finally shows up, the three of you who hadn't already guessed it can find out that it's the one with Alex's half-dead body in it. Lexie and Mark are ... concerned.
After the commercials -- including one for Katherine Heigl's Killers, which I honestly hope does well, because sorry haters, I'm the last person in America who doesn't hate her guts -- Richard has made it to the barricade in front of the hospital. There, he's met by a cop played by Tom Irwin, aka Graham Chase, aka Angela's dad from My So-Called Life! Officer Graham explains that a shooter "took down one of the doctors" and they're not sure if he's still inside. Richard makes to rush inside, but Graham blocks him. No one in, no one out, no exceptions. Richard is frustrated but he ultimately abides by Officer Graham. Cute Ryan Devlin shows up at the barricade with Mandy Moore's pizza, wondering what's going on. Again: Mandy Moore's TOTALLY gonna die, right?