How should I start chapter 2 after a dramatic cliffhanger?

I'm writing a book and have everything planned from the middle of chapter two onward. I have chapter one finished and it ended with a very dramatic cliffhanger (of which main characters whose names you don't know yet are all knocked unconscious). Now the question is how should I START chapter 2? Like, should I have them wake up, have the culprit enter the room and wake them up, describe something in the scenery like a sound or something, etc... After the first paragraph I should be able to get going smoothly, I just need that paragraph...