Dan Rodricks: Baltimore and the nation need a sustained gun buyback and campaign against violence

Horrible history: Between May and December of 1974, four Baltimore police officers were fatally shot in the line of duty. The men ranged in age from 33 to 22, their tours with the department from 12 to two years. One officer was Black, the other three white. Three of the men were married with children. A fugitive shot Detective Sgt. Frank Grunder in front of a church on Harford Road.