After a warning on the school intercom, a gunman with an AR-15-style rifle killed a teacher and a student while others jumped from windows

As a 19-year-old gunman walked through the St. Louis high school’s hallways with an AR-15-style rifle and over 600 rounds of ammunition, frightened students and teachers locked classroom doors and huddled in corners.

​As a 19-year-old gunman walked through the St. Louis high school’s hallways with an AR-15-style rifle and over 600 rounds of ammunition, frightened students and teachers locked classroom doors and huddled in corners.