Anderson Cooper 360

2 Mass Shootings Only Hours Apart; At Least 29 Killed; 20 Killed In El Paso, 9 Dead In Dayton Mass Shootings; Police: 9 Dead, 31 Injured In Dayton Shooting; Authorities Believe El Paso Gunman Posted Racist, Anti-Immigration "Manifesto" Online; El Paso Mother Killed Shielding Her Baby From Gunfire; Democrats Call For Senate To Be Called Back Into Session To Deal With Long-Stalled Gun Control Legislation; Parents Of Parkland Victim In El Paso Area; Say People Need To "Spring Into Action" To Stop Gun Violence via Knit