REDWOOD CITY, Calif. -- Thanks to a single voice speaking up, a potential school attack was prevented, according to a nonprofit created after the tragic Sandy Hook Elementary School shooting. Nicole Hockley's son Dylan was one of 20 children killed in 2012 at the Sandy Hook Elementary School shooting. On Monday, the organization claimed they helped stop a potential school attack within the Sequoia Union High School District out of Redwood City, California. Sandy Hook Promise also claims the posts included an image of the school. Editorial Note: The Atherton Police Department clarified details ABC7 News in San Francisco received from Sandy Hook Promise about the potential threat.