A teacher props a door open for airflow; a student slips out to the parking lot; a coach leaves a side door ajar after practice. In 61.7% of doors involved in active shooter attacks, the openings meant to protect students were unlocked or held open.

A new study funded by the Security Industry Association (SIA), Silver Spring, Md., complied by the ALERRT Center at Texas State University, San Marcos, Texas, found that noncompliance with security protocols and locking procedures—not the door hardware itself—were primary contributing factors to security breaches in active shooter incidents.

“The Role of Locked Doors and Access Control in School-Base d Active Shooter Events” (2026)

examined door locks and physical access-control in real-world K–12 school shootings. The study gleaned data from 54 events between 2000 and 2025, four averted incidents and two case studies: Robb Elementary in Uvalde, Texas, in 2022 and Evergreen High School in Evergreen, Colo., in 2025. Glass was identified as the primary point of vulnerability (no locking mechanism in the dataset was defeated mechanically) and of 47 doors with known status, 24 were unlocked and five were propped open.

Secured doors make a difference

Secured doors, the study concluded, correlated with dramatically fewer casualties. Time and space created by a locked door “redirected the trajectory of an attack,” and when integrated within institutional preparedness, training and response systems, that value was further magnified.

In seven of the 54 incidents (13%), a security system or procedure designed to prevent unauthorized entry was in place but was bypassed or forcibly breached. Of the 47 doors with known status, 51.1% were unlocked, 38.3% were locked and 10.6% were propped open or unsecured.

A direct correlation emerged between the status of the door and victim outcomes, according to the study. Behind secured doors (locked or barricaded), only 16.7% of incidents resulted in a casualty. When doors were unsecured, that figure rose to 50%.

The study recommended the following:

1. Ensure every classroom door has a functional lock that can be engaged from inside the room. The difference in potential casualty between secured and unsecured doors was the “largest and most consistent effect” observed.
2. Secure all exterior doors during school hours, with controlled visitor access through a single monitored entry point. Locked exterior doors either prevented entry or delayed access long enough for intervention by law enforcement.
3. Assess and upgrade glazing materials on exterior doors and classroom doors with glass features. Doors with functional locks were not breached, but perpetrators gained access by shooting though glass.
4. Establish and enforce a culture of compliance with door security protocols.
5. Invest in rapid lockdown capability, including training, alert systems and staff empowerment.
6. Tailor security strategies to school level. Different schools have various threat levels to be considered.
7. Eliminate the use of magnetic strips /door latch magnets and aftermarket door props. “Magnetic strips create an ambiguous security state in which a door appears closed and secured but is functionally unlocked.”
8. Establish standardized protocols for documenting door and access-control hardware during post-incident investigations. Details such as the lock type, door construction and locking mechanism status are critical to investigations and security recommendations. (Note: The ALERRT Center is developing a guide and template to standardize post-incident documentation of security hardware and other data.)