kurt gregory has more. >> reporter: just after lunchtime, a terrifying scene. reports of gunfire at ronald mcnair discovery learning academy near atlanta. the children were escorted to the back of the school grounds for safety as dozens of law enforcement agents scoured the campus. >> i never thought something like that would happen in my neighborhood, period. >> reporter: police say a 20-year-old michael brandon hill carrying an ak-47 and other weapons slipped past a buzzer security system and into the school by following someone who was authorized to be there. >> he didn't get any further than the front office. he barricaded himself with a couple office employees. >> reporter: as police arrived, the gunman left the office firing at least half a dozen rounds at responding officers. >> the officers were able to return fire. when they saw him in -- alone. >> reporter: when police fired back, the suspect dropped to the ground and surrendered. >> my husband called and said, hey, the baby is -- there's a gunman at his school. and i'm like, what? >> reporter: hundre