Geoff Bennett:

We start tonight in Georgia, where authorities say a gunman opened fire at a high school, killing four people, two students and two teachers. At least nine others were wounded. Police say they have arrested a student who is the suspect. And investigators say they do not yet know a motive.

This morning, about an hour outside of Atlanta, all-too-familiar scenes of chaos, ambulances and police cars racing to Apalachee High School in Barrow County, Georgia after reports of an active shooter. Dozens of emergency vehicles and a medevac helicopter descended on the school grounds as students sought safety on the football field while parents worried sick.