What is wrong with this 6 yr old boy?

He tells me he thinks about hurting his 19 mth old sister, he tears up, destroys everything he touches he ripped all kinds of holes in our trampoline net and then got mad at his father and I cause we said he was in trouble and not aloud to jump for awhile then he rips a huge hole and now it has to be replaced and it's only a yr. old. He has been ripping pages out of books and one book he tore out the word bottle cause he said he hates that word cause it drives him crazy. So As I am talking to him I ask him " am I wasting my time talking to you about this?". He replies "yes...........I like to call it burning daylight.". WHAT IS WRONG WITH THIS KID? The list goes on and on and on we are in the process of trying to get him help but I really don't know if he can be helped! Sometimes I kinda feel scared in my own home and that is not normal.