In October 2013, Avonte Oquendo, a 14-year-old boy with autism, disappeared from his school in the Queens section of New York City. Video surveillance showed that he had run out of the school building through an unguarded door. A few months later, his remains were found in the East River.

In response to the tragedy, the New York City Council enacted “Avonte’s Law,” which directs the city’s school system to evaluate the exterior doors in all its elementary and special-needs schools to determine which ones should be equipped with alarms, so school personnel can be alerted and react when someone is opening a door without authorization. By May 15, the school system must provide a timeline to the City Council for installing such alarms.

Avonte’s death is yet another example of the critical role that doors have in providing security for education institutions. Doors in school buildings often have to address contradictory needs: Let people in while keeping people out. And as Avonte’s case shows, they also must let people out while keeping people from getting out.

A guide from the U.S. Department of Homeland Security, “Primer to Design Safe School Projects in Case of Terrorist Attacks and School Shootings,” recommends upgrading door security in the way that New York City is considering.

“Doors that are vulnerable to unauthorized use, when students open them from inside the building, can be made more secure by installing door alarms, delayed opening devices, or sensors or cameras monitoring doors from the central office,” the guide says.