As my colleague Liliana Segura noted on Twitter this morning, the documented killing of black Americans by police officers has become so routine that it is hard for even the racists who seek to justify the slaughter in online comment threads to keep up.

For the news media, one way to frame these stories as something new is to focus on the technology, which now makes it possible for eyewitnesses to record and disseminate the killings and for those outraged by the images instantly appearing on their screens to register their discontent without even looking up from their phones.

That’s why the first reports on the killing of Philando Castile, a 32-year-old cafeteria supervisor at a Montessori School in St. Paul, Minnesota, who was shot while reaching for his license during a traffic stop on Wednesday night, included a comment from a Facebook spokesperson. The aftermath of the shooting, as Castile bled to death in the front seat of a car, was streamed live on the social network from the phone of Castile’s distraught girlfriend.

The video stream starts just after the shooting, with images of Castile still strapped into his seat, his white T-shirt covered in blood, as his girlfriend says to him, “Stay with me.” (The video is reversed, like a reflection in a mirror, so that the injured driver appears to be on the right rather than the left of the car, apparently because the woman was using the phone’s forward-facing camera.)

“We got pulled over for a busted tail light in the back,” she explains. She adds that he is “licensed to carry” a gun, but was simply “trying to get his ID and his wallet out of his pocket and he let the officer know that he was, that he had a firearm and he was reaching for his wallet and the officer just shot him in his arm. We’re waiting for a backup.”

The officer outside the car then shouts at the woman to keep her hands where he can see them. As she says, “I will, sir, no worries, I will,” the camera pans across to reveal the officer standing outside the car, training his gun on the couple. He then appears to scream, “Fuck!”

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A screen shot from the Facebook video stream of Philando Castile’s killing.

Lavish Reynolds via Facebook

The woman then resumes explaining what happened, saying, “He just shot his arm off; we got pulled over on Larpenteur,” a street in the Falcon Heights neighborhood of St. Paul. The officer, who sounds like he might be crying, then interrupts with his self-justification, screaming, “I told him not to reach for it, I told him to get his hand off it!” The woman replies: “You told him to get his ID, sir, you told him to get his driver’s license.”

“Oh my god, please don’t tell me he’s dead,” she then says. “Please don’t tell me my boyfriend just went like that.”

Moments later, as the police backup arrives and the woman is told to leave the car, she can be heard asking about the 4-year-old girl who watched the whole scene unfold from the back seat. “Where’s my daughter? You got my daughter?”

As the woman was arrested, the phone was forced from her hand but kept recording, and she could be heard telling anyone who might have been watching the live stream, “They threw my phone, Facebook.” The stream continues for nearly eight more minutes, recording her interaction with the officers and the face of her daughter once they were reunited in the back seat of a police car.

Near the end of the clip, as the woman breaks down, screaming and crying, a transcript of the video shows that her young daughter tries to comfort her.

“That’s the police officer over there that did it with the black on,” she says. “I can’t really do shit because they have me handcuffed.”

“It’s OK, mommy,” her daughter says.

“I can’t believe they just did this,” she adds, before screaming and breaking down in sobs.

“It’s OK, I’m right here with you,” the little girl says.

Castile was taken to a hospital in Minneapolis, where he died a short time later. His family told WCCO, a CBS affiliate, that the video was streamed to Facebook by his girlfriend, Diamond Reynolds, who added just one word of commentary: “Police.”

Valerie Castile, the dead man’s mother, said she had no doubt he told the police officer he had a firearm and was legally permitted to carry it. “I’m sure he did, because that’s something we always discussed: comply. That’s the key thing, the key thing in order to try to survive being stopped by the police is to try to comply. Whatever they ask you to do, do it. Don’t say nothing, just do whatever they want you to do.”

“So what’s the difference in complying,” she asked, “and you get killed anyway?”

“They’re still saying there’s no profiling,” she added. “But it is, it is. We’re being hunted, every day. It’s a silent war against African-American people, as a whole.”

Reynolds told the press later that she was held by the police until 5 a.m. and her boyfriend had done nothing threatening.

The outraged reaction on social networks was reinforced for many by the fact that many people who watched the video were still shocked and traumatized from viewing another clip, one that showed the fatal shooting of another African-American man, Alton Sterling, whose name was converted into a trending hashtag one day earlier after his killing by officers in Baton Rouge, Louisiana.

The first, distressing video of Sterling being shot at point-blank range, while being restrained by two officers outside a market where he was selling CDs, was uploaded to the web by a local activist group that tracks police violence, which also made an old story seem somehow new.

That visceral record of what looked very like an extrajudicial execution was quickly followed by an even more graphic, close-up view recorded by the owner of the Triple S Food Mart, Abdullah Muflahi, which cast doubt on the officers’ claim that Sterling was shot while reaching for a gun in his pocket.

Muflahi also told the Baton Rouge Advocate that, as his video showed, Sterling was not holding a gun when he was fatally wounded.

Muflahi’s lawyer told The Advocate that the store owner had not turned his video over to the police because he doesn’t trust the Baton Rouge Police Department, but he did provide the clip to the FBI.

Sterling’s death was followed by heartbreaking images of his 15-year-old son breaking down on live television.

The United States attorney in Baton Rouge, Walt Green, announced on Wednesday that his office and the FBI’s New Orleans Division had opened a civil rights investigation into the killing of Sterling.