Flailing away with two knives, a 16-year-old boy with a “blank expression” stabbed and slashed 19 students and a police officer in the crowded halls of his suburban Pittsburgh high school Wednesday before an assistant principal tackled him. At least five students were critically wounded, including a boy who was on a ventilator after a knife pierced his liver, missing his heart and aorta by only millimeters, doctors said. See the footage below!
