Blackwater defendants plead not guilty

WASHINGTON (CNN) - Five former security guards from Blackwater Worldwide pleaded not guilty Tuesday to charges of voluntary manslaughter and other serious crimes stemming from their involvement in a September 16, 2007, shooting incident in a Baghdad square in which 17 Iraqis were killed.

Each of the former guards has been charged with 14 counts of manslaughter, 20 counts of attempted manslaughter and one count of using a firearm in the commission of a violent crime.

If convicted, the defendants would face a maximum sentence of 10 years in prison for each manslaughter count, seven years in prison for each count of attempted manslaughter, and a 30-year mandatory minimum sentence for the firearms charge.