Boulder mass shooting — how it happened

A gunman opened fire at a Boulder, Colorado grocery store, killing multiple people, including the first police officer on the scene. The shooting began in the parking lot and continued inside the store. Witnesses reported hearing shots and seeing bodies. Some survivors escaped through the back service entrance, while others exited through the front. Video footage showed a partially clothed man being arrested and taken into custody with a leg injury.

What new insight or understanding did you gain from this video?