Officers shot in Ferguson

St. Louis County Prosecutor Robert McCulloch, left, speaks during a news conference as St. Louis County Police Chief Jon Belmar listens March 15 in Clayton, Missouri.   (Jeff Roberson/AP)

Police officials conduct an investigation in the Ferguson, Mo., neighborhood near the area of the overnight shooting of two police officers on March 12, 2015.   (Michael B. Thomas, AFP/Getty Images)

Police mobilize in the parking lot of the Ferguson Police Department headquarters after two officers were shot early on March 12.  (Laurie Skrivan / Associated Press)

Police gather outside the Ferguson Police Department early on March 12 after two officers were shot.  (Jeff Roberson / Associated Press)

Police canvass the area as they investigate the scene where two police officers were shot outside the Ferguson Police Department early on March 12.  (Jeff Roberson / Associated Press)

Police shine a light on a helmet as they investigate the scene where two police officers were shot outside the Ferguson Police Department early on March 12.  (Jeff Roberson / Associated Press)