<P> Meanwhile, in the operating room, Derek's heartbeat returns to normal, and everyone is relieved . Outside the hospital, Arizona and Callie reinstate their relationship when Callie says she doesn't want to have a baby if it means she can't be with Arizona . Arizona agrees to have a baby because she says that she doesn't want to stop Callie from being an excellent mother . Mark and Lexie show up at the other hospital . Alex is out of surgery . Lexie goes to Alex . Mark watches Lexie take Alex's hand . Meredith takes another look at her positive pregnancy test, and throws it out . </P> <P> The episode was written by showrunner Shonda Rhimes and directed by Rob Corn . In an interview Rhimes told that the writing of the two - part season six finale, caused her struggle . She elaborated on this: </P> <Table> <Tr> <Td> "</Td> <Td> It hurt to write this finale . It literally hurt me . Because in order to write these episodes, I had to walk in the shoes of (the shooter). I had to think like a shooter . A person who would shoot Reed and Alex and Charles . A person who would shoot Derek . By the time I finished writing part one, I was sick . And depressed . Because my McDreamy was lying on my beloved catwalk dying . Mer is screaming and he is dying . And, before you have me shot up with Thorazine and placed in a strait jacket, yes, I DO I know it's only a TV show, I'm not insane, but dude...it felt too real . It felt WAY too real . </Td> <Td>" </Td> </Tr> </Table> <Tr> <Td> "</Td> <Td> It hurt to write this finale . It literally hurt me . Because in order to write these episodes, I had to walk in the shoes of (the shooter). I had to think like a shooter . A person who would shoot Reed and Alex and Charles . A person who would shoot Derek . By the time I finished writing part one, I was sick . And depressed . Because my McDreamy was lying on my beloved catwalk dying . Mer is screaming and he is dying . And, before you have me shot up with Thorazine and placed in a strait jacket, yes, I DO I know it's only a TV show, I'm not insane, but dude...it felt too real . It felt WAY too real . </Td> <Td>" </Td> </Tr>

When does the shooting occur in grey's anatomy