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A police officer stands by the scene outside Franklin Regional High School where more then a dozen students were stabbed by a knife wielding suspect on Wednesday, April 9, 2014, in Murrysville, Pa., near Pittsburgh. The suspect, a male student, was taken into custody and is being questioned. (AP Photo/Tribune Review, Brian F. Henry)  PITTSBURGH OUT
A police officer stands by the scene outside Franklin Regional High School where more then a dozen students were stabbed by a knife wielding suspect on Wednesday, April 9, 2014, in Murrysville, Pa., near Pittsburgh. The suspect, a male student, was taken into custody and is being questioned. (AP Photo/Tribune Review, Brian F. Henry)  PITTSBURGH OUT

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    Hear police radio call after stabbing

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Hear police radio call after stabbing

CNN's Evan Perez dissects the police radio transmissions from Franklin Regional Senior High School in Pennsylvania.

Hear police radio call after stabbing

CNN's Evan Perez dissects the police radio transmissions from Franklin Regional Senior High School in Pennsylvania.