In the attack at the private Jewish school Ozar Hatorah on Monday, a man wearing a motorcycle helmet and driving a motor scooter pulled up and shot a teacher and three children -- two of them the teacher's young sons -- in the head.
"We put a motor in the cheek pad of the helmet so if you do not notice the object it will vibrate and give you a tactile warning that there's something to the right or left, " said Mr Moore.