what happened?

We had some friends over for a dinner party and I hear a faint hysterical cry coming from the playroom. So I immediately head for the playroom and find Greta crying and her brothers standing there looking guilty. Here is the conversation that ensued:
Me: What happened?

Gunnar: It was Sawyer. He slammed the door on her hand.

Me: Sawyer, is that true? Did you slam the door on her hand?

Sawyer: No, No I did NOT!

Gunnar: Yes, you did! I saw it. 

Sawyer: No, I didn't slam the door on her hand!

Me: Then why is she crying and you look guilty?

Sawyer: Because I slammed the door on her head.