Yesterday, Thursday 18 June, white supremacist Dylann Roof killed nine black women and men at a church in South Carolina.
In the wake of the shooting we look back at this moving Tedx Talk by Nicole Hockley, the mother of Dylan Hockley, who was killed in the Sandy Hook school shootings in Connecticut in 2012. He was six years old.
Nicole discusses gun violence in the United States, and what everybody can do to stop it.
