Brown University shooting manhunt enters day three as police search for gunman who killed Ella Cook, Mukhammad Aziz Umurzokov and injured nine students.

The ongoing effort to find a man who walked onto Brown University ’s campus during a busy exam season and shot nearly a dozen students in a crowded lecture hall has raised questions about the school's security systems and the urgency of the investigation itself.

Rob Reiner and Michele Singer Reiner's son Nick has been arrested in connection with their deaths. And, authorities have released new images to help identify the gunman in the Brown University shooting.

An alert sent by Brown University told students to lock doors, silence phones and stay hidden until further notice.