OAHU, HI - FEBRUARY 18: A kindergarten student hides under her desk during a classroom lockdown drill February 18, 2003 in Oahu, Hawaii. Lockdown procedure is used to protect school children from possible threats on campus such as intruders, terrorism or military attack. (Photo by Phil Mislinski/Getty Images)

OAHU, HI - FEBRUARY 18: Kindergarten students lie on the floor during a classroom lockdown drill February 18, 2003 in Oahu, Hawaii. Lockdown procedure is used to protect school children from possible threats on campus such as intruders, terrorism or military attack. (Photo by Phil Mislinski/Getty Images)

Playful boy kid hiding under the table

This Wednesday, June 8, 2016 photo shows a wall at the Cure Violence headquarters in Staten Island, New York. The Cure Violence team walks the streets to defuse arguments that can lead to shootings and match people with job training and counseling. (AP Photo/Seth Wenig)

In this frame grab from video provided by WPLG-TV, students from the Marjory Stoneman Douglas High School in Parkland, Fla., evacuate the school following a shooting there on Wednesday, Feb. 14, 2018. (WPLG-TV via AP) NYTCREDIT: WPLG-TV, via Associated Press

Spokane police officers Chris Johnson, left, and Joseph Matt are filmed with fleeing student and teacher actors as they clear a hallway during a simulated active shooter event at North Central High School high, Monday, May 21, 2018. The Center for Personal Protection and Safety and ILF Media Productions of Spokane are producing a 12-minute video call “Beyond Lockdown- Preventing and Responding to Extreme School Violence, Colin Mulvany/THE SPOKESMAN-REVIEW