U.S : Students Are Seen Running For Their Lives As Ex-student, 19, Carrying An AR-15 And 600 Rounds of Ammunition Kills Teacher And Teenage StudentĀ 

A shocking video shows students escaping a classroom at a high school in St. Louis where a shooter entered the school through a locked door and killed a teacher and a student on Monday.

The video, taken from inside a classroom, depicts the mayhem caused by shooter while the daughter of the teacher who was killed revealed her mother had raised concerns over school security.

19-year-old Orlando Harris used an AR-15 style rifle in the attack and brought over 600 rounds of ammunition to the school, and police also found a notebook detailing his desire to conduct the shooting.