Threats against schools are increasing following a shooting at a high school in Barrow County, Ga. It is a recurring phenomenon that follows many tragic events.

ATLANTA (AP) — Students at Apalachee High School outside Atlanta will return to campus for half-days beginning next week, Barrow County school officials announced, after a Sept. 4 shooting that killed four people and injured nine others.

Schools across the U.S. have been rocked by a spate of false threats of violence in recent weeks, forcing them to evacuate or temporarily close. Why it matters: Threats of bombs, shooters and other dangers disrupt learning and stir community-wide anxiety about school safety.