"That's a weapon," says the helicopter pilot.
"Yeah," says the gunner.
CBS News Justice and Homeland Security correspondent Bob Orr reports that the aerial assault plays out over 40 minutes with an Apache helicopter pilot with the call sign Crazy Horse one-eight repeatedly requesting permission to fire on a group of men he believes to be insurgents.
"Hotel two-six, this is crazy horse one-eight," says the pilot. "Have individuals with weapons."
The pilot is told, "You're clear."
"Alright, firing," says the pilot.
The Apache and a second gunship open up with machine guns as the men on the ground try to flee. A short time later they ask again for permission to fire.
"Come on! Let us shoot!" says the pilot. "Bushmaster, Crazy Horse one-eight."
"This is bushmaster seven," a commander tells the pilot. "Go ahead."
Someone in the helicopter says, "Roger. We have a black SUV or bongo truck picking up the bodies."
"Ah, yeah, look at those dead bastards. Nice," one shooter says.
Among those believed to have been killed in that attack was Reuters photographer Namir Noor-Eldeen, 22, and his driver Saeed Chmagh, 40. Two children also were wounded. More than one dozen people were killed. For two years the Pentagon has refused to release the video or the findings of its internal investigation.
The military official, who spoke on condition of anonymity because he was not authorized to speak publicly about the video, said the military could not confirm the identities of the Reuters employees in the film.
According to U.S. officials, the pilots arrived at the scene to find a group of men approaching the fight with what looked to be AK-47s slung over their shoulders and at least one rocket-propelled grenade.
A military investigation later concluded that what was thought to be an RPG was really a long-range photography lens; likewise, the camera looked like an AK-47.
The helicopters later destroy a vehicle that arrived on the scene to help a wounded man. When ground forces arrive, the video shows what looks to be a child being carried from the vehicle and U.S. troops saying the child should be sent to a local Iraqi hospital.
"Well, it's their fault bringing their kids into the battle," a cockpit voice can be heard saying.
According to a July 19 summary of the investigation, obtained by The Associated Press, U.S. troops acted appropriately. Reuters employees were likely "intermixed among the insurgents" and difficult to distinguish because of their equipment, the document states.
"It is worth noting the fact that insurgent groups often video and photograph friendly activity and insurgent attacks against friendly forces for use in training videos and for use as propaganda to exploit or highlight their capabilities," the document concludes.
Wikileaks says it obtained the video from whistleblowers and published it to prove the helicopters were not under fire or acting in self defense.
It appears from the tape that at least some of those hit on the ground were unarmed. But a journalist who was in the general area that same day says it's important to remember it was a hectic, violent and uneasy day.