Baltimore has very serious and endemic issues with crime, drugs, poverty and government -- all of which combine to result in an extremely high murder rate. The numbers have improved since the historic peak in 1993 (353 murders), and Baltimore is no longer the #1 city in murders per capita in the US, but it's still not good.

If you're interested, there are several excellent explorations of the particulars of Baltimore's problems (which are present, usually to a lesser extent, in many other cities) from David Simon:

  - Homicide: A Year on the Killing Streets (book)
  - Homicide: Life on the Streets (TV series)
  - The Corner: A Year in the Life of an Inner-City Neighborhood (book)
  - The Corner (TV miniseries)
  - The Wire (TV series)