A school safety officer for the high school was alerted by staff that an assault had happened in one of the classrooms, police said.

"Schools must be safe places,” State Superintendent of Public Instruction Tom Horne said, calling the incident a "terrible tragedy"

A student was stabbed to death and his alleged attacker was hospitalized after the two teen boys got into an argument inside an Arizona high school classroom just two weeks into the school year — sending students and their parents into panic mode.