When Aizen returns to the Central 46, he is immediately attacked by 15 Central 46 Shinigami guards.
Pointless. Have none of you learnt? If the Gotei 13 cannot defeat me, then none of you have a shadow of a chance.
Aizen then proceeds to use Senka to kill 5 Shinigami. He then leaves his back open to attack, only for 3 attacking Shinigami to be decapitated.
Now there are only 7 of you left, and I haven't even begun to show the smallest fraction of my strength. Hado 73: Soren Sokatsui.
Aizen then proceeds to kill the remaining Shinigami using Soren Sokatsui. He then turns around to speak to the officials in the Central 46 building.
Central 46, while you may think that I'm here to kill you, I am not. I am instead here to make a deal. If you banish the remaining Shinigami from Soul Society, then I will let you all live. Fail to cooperate, and the consequences will be detrimental for you.
As soon as this deal is proposed, the Central 46 officials refuse.
Foolish of you, hmph. It matters not. You will all fall slave to my blade then. Kudakero (Shatter), Kyouka Suigetsu.
And with that, the Central 46 was under Kyouka Suigetsu's Kanzen Saimin (Complete Hypnosis).