Newtown Shooting Timeline: A Grim Day Marked By Confusion At Connecticut Elementary School

Shortly after classes began at Sandy Hook Elementary School in Newtown, Conn., a gunman opened fire. Police arrived within minutes, but not before 27 people were killed, including 20 children, six adults and the shooter, according to the Associated Press. Police are still investigating.

Below, key moments and expressions of sadness from a grim day as it unfolded.