Breaking News from CBS

• How tornado warning systems work

  Despite advanced technology, Moore, Oklahoma's tornado warning system still relies on someone pulling a lever to activate the alarm

• Video: Mother and daughter share stories of survival

  Courtney Brown and her second-grade class took shelter in a hallway at their school; Courtney's mom rushed to what was left of the school to search for her children. The mother and daughter tell Norah O'Donnell their story.

• Oklahoma native's home destroyed for the second time

  Nancy Davis, 94, helped save lives during the tornado by sharing her shelter, built after the historic 1999 twister in Moore

• Okla. family mourns child killed at school following tornado

  Joshua Hornsby raced to find his 9-year-old daughter at school when the tornado hit; he got there 10 minutes too late

• Video: The next day: Search-and-rescue operations become search-and-recovery efforts

  The frantic search-and-rescue operations following Monday's tornado became a grim search-and-recovery effort Tuesday. Anna Werner reports.