The department would not specify what that item was. Parents waiting outside the school to reunite with their children told 12News the deadly altercation has them worried for their students' safety, especially when weapon detection systems are in place on campus.

A Phoenix police officer working as a school safety officer at Maryvale High School was alerted of an assault in one of the classrooms, police said.

Chris Aguilar, 16, was charged with second-degree murder in the fatal stabbing of another student, 16-year-old Michael Montoya II.