FEBRUARY 15--The man who used an AR-15 to gun down students and staff at a Florida high school confessed to the killing spree, according to police who interrogated him following yesterday’s mass murder.

Nikolas Cruz, 19, told cops that he “began shooting students that he saw in the hallways and on school grounds” at the Marjory Stoneman Douglas High School in Parkland, according to a court complaint.

Cruz--who was expelled last year from the school--said that he “brought additional loaded magazines to the school campus and kept them hidden in a backpack until he got on campus to begin his assault.”

When terrified students began to flee, Cruz discarded his assault rifle and tactical vest in a bid to blend in with the pupils. He was subsequently arrested about an hour later in nearby Coral Springs.

Cruz, who was charged today with murdering 17 victims, took an Uber to the high school. He arrived with the AR-15 inside a black duffel bag.

A trace on the rifle revealed that Cruz purchased the weapon in February 2017 (though the seller was not identified in the complaint). (3 pages)