Cellphone footage shows students huddled in their classroom during a shooting at Oxford High School in Michigan. RELATED: https://youtu.be/pGzDjCJ2Zok Police were investigating what led to a deadly shooting at a Michigan high school where a 15-year-old student opened fire, killing three teenagers and injuring eight people. Oxford High School students described a chaotic scene in which a voice came over the intercom to announce an active shooter and they didn't know whether it was a drill. Then teachers rushed to lock and barricade doors and cover windows. Students were in tears and texted loved ones. » Subscribe to USA TODAY: http://bit.ly/1xa3XAh » Watch more on this and other topics from USA TODAY: https://bit.ly/3dbhy8i » USA TODAY delivers current local and national news, sports, entertainment, finance, technology, and more through award-winning journalism, photos, videos and VR. #Michigan #Shooting #OxfordHighSchool