(03/29) GAS Hour 1 - Nashville Hero Cops 

Metro Nashville Police officers are being hailed as heroes as they ended the mass shooting at Covenant School with urgency. Katherine Koonce, 60, the headmistress of Covenant School, was found dead in a hallway. Police believe she confronted the shooter to try and save the kids. More than 1,000 tech leaders, researchers and others signed an open letter that urged a moratorium on the development of powerful A.I. systems.