Follow live updates as police seek to identify masked person as manhunt enters fourth day for Brown University shooting

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

Ret. FBI supervisory special agent Jason Pack analyzes the Brown University shooting suspect’s possible motivation and applauds first responders on ‘The Big Weekend Show.’

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