The Facebook live video of the aftermath of the police shooting of Philando Castile went down for a few hours shortly after it reached more than 1 million viewers. Facebook blames a technical glitch. (Jhaan Elker/The Washington Post)

Seconds after shooting the man he had just pulled over, the police officer yelled at a woman in the passenger seat: “Ma’am, keep your hands where they are.”

Diamond “Lavish” Reynolds watched blood drench her boyfriend’s white shirt. She did not scream. She did not cry. Her language remained polite.

“I will, sir,” she replied calmly. “No worries. I will.”

Reynolds recorded the conversation on her phone, live-streaming a routine traffic stop that turned deadly and caught the world’s attention. As the officer shouted expletives, she continued to narrate with startling composure.

“He just shot his arm off,” Reynolds matter-of-factly explained to viewers.

By Thursday morning, the roughly 10-minute Facebook video had garnered more than 3 million views. Many viewers wondered how Reynolds maintained such a calm demeanor. Was it psychological shock or the well-practiced behavior of a black woman who feared law enforcement?

Speaking to reporters Thursday, Reynolds said she found strength for her four-year-old daughter, who also witnessed the shooting from the backseat.

“My daughter told me stay strong, and that’s what I had to do," she said. "My daughter told me, ‘Don’t cry,’ and that’s what I had to do. My daughter prayed for me."

As she boarded a flight from Indianapolis to Minnesota on Thursday evening, Dafina Doty, Reynolds’s mother, said she raised her daughter to treat authorities with respect — no matter what. The cool-headed woman in the video, she said, reflected that upbringing.  

“She’s a productive person,” Doty said. “She’s well spoken. She’s a strong young woman.”

Trauma experts say Reynolds's response wasn't surprising. Jim Hopper, a psychology instructor at Harvard Medical School, watched the footage Thursday and said her behavior was consistent with what he calls a dissociative state.

In the immediate aftermath of horrific violence, he said, victims don’t always sob. Reynolds's face appeared stoic. Her voice remained steady: “You told him to get his ID, sir. His driver’s license,” she told the police officer. But it doesn't mean she wasn't afraid.

“People are literally not feeling in their body what’s going on,” Hopper said. “That circuitry can basically shut down. This is the brain on horror.”

In the car, as Castile moaned beside her, Reynolds kept talking, repeating similar phrases:

“Please, Jesus, don’t tell me that he’s gone.”

“Please don’t tell me he’s gone.”

“Please, officer, don’t tell me that you just did this to him.”

It's easier to appear unfazed, Hopper said, if a victim has something to focus on. Sometimes, it’s helping others. Sometimes, it’s calling for help. In Reynolds’s case, it’s telling the world what happened to Castile.

“She’s grasping for dear life to these phrases, to this phone," he said. "You can think of it as a life raft to try to get through this.”

Hopper, who studies the impact of trauma on the brain, compared Reynolds's reaction to what he has witnessed among victims of sexual assault. When they report attacks to authorities, he said, they often sound like they're reading from a grocery list. Trauma can trigger pain-regulating hormones, which can make a victim appear to be relaxed, even apathetic.

Academic research has found that the physical manifestation of trauma can be subtle. A 2014 report from the Substance Abuse and Mental Health Services Administration emphasizes that people don’t respond to trauma like actors in Hollywood movies. “Survivors’ immediate reactions in the aftermath of trauma are quite complicated and are affected by their own experiences,” the authors wrote. “Coping styles vary from action oriented to reflective and from emotionally expressive to reticent.”

Another study from the Journal of Aggression, Maltreatment and Trauma found that the bulk of a victim’s emotional response often spikes in the days after a traumatic event, rather than in real time.

Monnica Williams, director of the Center for Mental Health Disparities at the University of Louisville, said a fear of police might have informed Reynolds’s behavior. The brain science professor, who studies racial trauma, said black children often grow up hearing about police mistreating black people.

“This becomes something that you might even expect,” Williams said. “All you have to do is turn on the television and see another black man has been shot.”

Projecting composure, for some, might be a premeditated survival strategy. “Being able to stay calm in a crisis — you preserve your life and protect your loved ones,” she said.

Pressing play, meanwhile, might have come naturally. In the days before the fatal stop, according to her profile page, Reynolds had used Facebook's live-stream feature to record herself rolling down the highway and hanging out with her daughter. She'd also shot footage of two men fighting.

"I wanted to put it on Facebook and go viral so the people could see," she told reporters Thursday. "I wanted the people to determine who was right and who was wrong.”

Then she wept.

"They took my lifeline," Reynolds said. "That was my best friend."

On social media, Twitter users offered another explanation. They lauded Reynolds's behavior as a deliberate act of defense.