2. Locking interior doors worked.
As in the vast majority of K-12 school shootings in the United States, not a single student or staff member was killed behind a locked interior door. Although many people have stated that staff and students should have evacuated, the report indicates that where lockdown was accomplished fast enough, no victims were killed.
Despite the fact that the locked front entry door was breached, the report indicates that no interior doors were breached by force. Keeping in mind that most of the staff and students in the school survived, this affords additional evidence that lockdown is still one of our most effective tools to prevent death in mass casualty school shootings.
Interestingly, the first instance of a successful school lockdown occurred less than 10 miles from Sandy Hook Elementary School in Danbury, Conn., in 1900. In that case, a teacher prevented a man with a gun from entering the school by securing the front door to the one-room schoolhouse.