Inside a white car was Mehasin Muhsin Kadhum, a 46-year-old doctor, and her 20-year-old son, Ahmed, who was driving. They were wrapping up errands that included picking up college applications for Kadhum's daughter.
By then the Blackwater convoy had entered the circle, and Iraqi officers were trying to stop vehicles as Ahmed approached. A Blackwater guard fired, killing Ahmed. One traffic officer, Sarhan Thiab, told me:
"The bullet went through the windshield and split his head open. His mother was holding him, screaming for help."
Within seconds, the guards intensified their assault using machine guns and grenades, killing Kadhum as well. When the shooting ended, 17 Iraqis lay injured in addition to the 14 killed. The victims included children, college students and professionals.
The killings triggered outrage and calls for accountability and justice. It was one of the darkest moments of the Iraq War, damaging the United States' reputation and its relationship with the Iraqi government.
When Washington refused to allow the contractors to be tried in Iraq, the incident became a symbol of unaccountable American power and forced a reassessment of the reliance on private security contractors in war zones.
Initially, the guards gave sworn statements to State Department investigators that they had fired on the white car because it was coming at them at high speed and did not stop. But many witnesses told me the car was moving slowly, in a nonthreatening manner.
Subsequently, U.S. military investigators would conclude that the Blackwater guards opened fire without provocation and used excessive force. In 2014, a federal jury found four guards guilty of killing the unarmed civilians.
But last week's reversal of the first-degree murder conviction of Nicholas Slatten, the former guard, is a major setback for the victims and families. He had been sentenced to life in prison.
The appeals courts also ordered resentencings for the three other former guards convicted of voluntary manslaughter and use of a machine gun in a violent crime. They received 30-year prison sentences.
An official at the Iraqi Embassy in Washington told my colleague Spencer Hsu that the killings are "still raw after all these years" and were an "egregious atrocity that these people committed."
Ironically, it was a discrepancy over who fired the first shots at the white car that led to the throwing out of the murder conviction. Prosecutors argued that Slatten had fired the first shots, but another defendant said that he had fired first.
The white car, I remember, sat at a bus stop on the edge of Nisoor Square for weeks after the killings. It was charred and shattered by the firepower.
Haitham Ahmed, who lost his wife and eldest son, wanted the car to remain visible as a reminder of the carnage. He told me that he wanted it left there until justice was served.
He, too, was a doctor. The family had had many opportunities to leave the country, but he said that he and his wife believed in the promise of a new Iraq. He felt pain, he said, when he saw doctors fleeing Iraq. His son, who was in the third year of medical school, was planning to become a surgeon like his parents.
"What I want is the law to prevail," Haitham Ahmed said in 2007. "I hope that this act will not go without punishment."