Students comfort each other at Arapahoe High School on Friday.
Credit Ed Andrieski / AP
A Colorado high school student with an apparent grudge against a teacher wounded a classmate with a shotgun before killing himself, chilling a state that's still trying to make sense of mass shootings at Columbine High School and an Aurora movie theater.
Quick-thinking students at Arapahoe High School on Friday alerted the targeted teacher, who quickly left the building. Police immediately locked down the scene on the eve of the Newtown massacre anniversary — a somber reminder of how commonplace school violence has become.