US President Joe Biden has condemned a "sick" epidemic of gun violence against children, one day after a school shooting left three students and three adult staff members dead in Nashville, where he plans a visit. "I never thought when I started my public life that guns would be the number one killer of children in America," Biden told an audience on Tuesday in North Carolina. "It's sick." The president later told reporters that planning is under way for him to meet with families of the victims in Tennessee. Firearms have surpassed car accidents as the leading cause of death for Americans aged 1 to 19, according to US Centers for Disease Control and Prevention data through 2021, the latest figures available. In the aftermath of the shooting, Biden has called on Congress to re-impose a ban on assault weapons. On Tuesday, he said high-powered, semi-automatic weapons are problematic not just because of their ability to fire multiple rounds quickly but also the damage their bullets do to the human body. "What in God's name does anyone need that for in America?," Biden said. The Nashville shooter, a 28-year-old who was fatally shot by officers at the scene, used two assault weapons and a handgun, police said. Australian Associated Press