Do I have the right to an independent psychological evaluation of my 5 year old son? Can his school evaluate him without my consent?

We are in the Irvington, NY school district. My son, kindergarten age 5, has kicked his teacher and threatened her and has hit an aid. We want him evaluated independently as we do not trust the school psychologist. She kept him sitting on the floor of her office for over 2 hours because he refused to speak to her. He eventually blurted out that he was going to booby trap the school. She then asked if he wanted to hurt people. Which he said yes. Her next question was if he wanted to kill people in the school. He again angrily replied yes. He was not allowed back into his class and eventually sent to the principals office where she asked if he wanted to hurt people and he replied, 'of course not'. A couple days later he was suspended for telling his teacher that he wanted to kill her (we feel this came directly from the psychologists questioning). The psychologist has told us that she thinks he is a threat to the school and we do not feel that she is competent.