Four former security guards from Blackwater Worldwide were convicted and jailed Wednesday for the part they played in the 2007 shooting in Baghdad's Nisour Square. The deadly attack was a dark mark on America's war in Iraq.

A Federal District Court jury found the 17 Iraqis' deaths was not part of a wartime defensive strategy, but rather a criminal act. The shooting reportedly began after a convoy of the guards began firing into a busy intersection.

The four men were convicted on a multitude of charges including murder, manslaughter and weapons related to the incident. The investigation was repeatedly road-blocked with setbacks, which created tension and even more mistrust among Iraqis toward American forces.

"This verdict is a resounding affirmation of the commitment of the American people to the rule of law, even in times of war," U.S. attorney in Washington, Ronald Machen Jr., said. "Seven years ago, these Blackwater contractors unleashed powerful sniper fire, machine guns and grenade launchers on innocent men, women and children. Today, they were held accountable for that outrageous attack and its devastating consequences for so many Iraqi families."

Nicholas Slatten, one of the defendants and a sniper who reportedly fired the first shots, was convicted of murder. The other three, Dustin Heard, Evan Liberty and Paul Slough, were each convicted of voluntary manslaughter and using a machine gun to carry out a violent crime. Jeremy Ridgeway, a fifth contractor, pleaded guilty to manslaughter and cooperated with prosecutors.

"Nick Slatten is innocent," Thomas Connolly, Slatten's lawyer, said after the verdicts' announcement. "We're disappointed that the jury found otherwise, but the jury's verdict does not change the reality of what happened - and what didn't happen - in Nisour Square."

While a sentencing date has not yet been set, Heard, Liberty and Slough, face a mandatory 30-year prison term for the machine gun charges. Slatten faces a possible life sentence.