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.

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

The Phoenix Union High School District superintendent says class will resume on a modified schedule with counseling services made available to students and staff.