LOS ANGELES — You’re a parent, volunteering to supervise recess at your child’s campus when suddenly you spot him. A masked shooter, armed to the teeth, heading straight into the building.

Do you consider yourself responsible for the students around you, and herd them to a safe place? Or do you try to locate your own child first?

Los Angeles Police Department Officer Charles Dinse posed this startling scenario recently to a group of 60 or so parents gathered in Woodland Hills, Calif., to hear his presentation on active-shooter drills. There is no right or wrong way to react to the scenario, said Dinse, but hypothetical situations like these are what schools need to grapple with in a post-Sandy Hook world.