Today we're bringing you an episode of Anderson Cooper 360. At least three teenagers were killed and eight people were injured in a shooting at a high school in Oxford, Michigan. The 15-year-old suspect, a sophomore at the school, was taken into custody after police responded to the shooting. Aiden Page is a senior at Oxford High School and barricaded in a classroom during the shooting. He tells Anderson Cooper about the moment he realized he was hearing gunshots. 

Plus, the CDC is expanding surveillance at four U.S. international airports to look for the Omicron variant of Covid-19 in travelers. CNN’s Chief Medical Correspondent Dr. Sanjay Gupta joins AC360 to discuss whether or not vaccines will help protect against the new variant.  

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