Law enforcement's response to the Uvalde school shooting

Police say the gunman that killed 19 children and 2 teachers at an elementary school in Uvalde, Texas on Tuesday was wearing body armor, carrying a rifle, and was able to get past multiple police office officers to barricade himself in a classroom. Kathy Guider, retired FBI special agent and VP of operations at Veracity IIR, joins CBS News to discuss how a shooting like this occurred.