I feel very much for this little boy.
Children learn what they are taught by others. Look at what he was taught. He needs help. He needs to know that what happened was not his fault. He also needs to know that it is wrong to act out what he was taught.
He needs councelling very badly, with a trained specialist. Talk with his parents, but be very discrete and sympathetic or they will feel that you are getting into business that does not concern you. I know I didn't say that right, but I hope you understand what I'm trying to say.
Get him help. Now.
Peace

and God bless and help this innocent child before he harms others like he was harmed.