Virginia Tech shooting - in pictures

Virginia Tech students pause to remember the police officer who was killed earlier on campus Photograph: Chris Keane/Reuters

A Virginia Tech student places flowers at a memorial to the 2007 shootings for the police officer who was killed that day Photograph: Chris Keane/Reuters

The memorial to the 2007 shootings at Virginia Tech Photograph: Sam Dean/AP

Virginia Tech police officers console one another as they move toward the scene where a fellow police officer was killed this week Photograph: Don Petersen/AP

Police secure the perimeter of Virginia Tech campus in Blacksburg Photograph: Sam Dean/AP

Police continue their investigation on the campus of of Virginia Tech Photograph: Jared Soares/Getty Images

A Montgomery County law enforcement officer stops a car on Duckpond Road after the multiple shooting had taken place Photograph: Kyle Green/AP

A police officer secures the scene where a gunman killed a police officer while students look on Photograph: Matt Gentry/AP

Police officials examine the body of a police officer shot dead in a parking lot Photograph: Don Petersen/AP