GWEN IFILL: Now to a police shooting of a Missouri teenager that sparked racial tension, violence and looting in a Saint Louis suburb over the weekend.

JEFFREY BROWN: It was all set in motion Saturday, when 18-year-old Michael Brown was shot repeatedly by a police officer in the Saint Louis suburb of Ferguson, Missouri. Brown was unarmed and witnesses maintained he was an innocent victim.

WOMAN: He was running. And then he turned around and put his arms up. He just stopped, put his hands up after he had gotten shot repeatedly.

JEFFREY BROWN: The chief of police of Saint Louis County, who's leading the investigation, said the incident began with a scuffle.

JON BELMAR, Chief, Saint Louis County, Missouri: It is our understanding at this point in the investigation that within the police car there was a struggle over the officer's weapon. There was at least one shot fired within the car.

JEFFREY BROWN: The officer was placed on administrative leave. His identity and race were not released.

But the killing sparked outrage and protests yesterday afternoon. And demonstrations continued into the night. Then came a candlelight vigil that began peacefully, but turned violent, as some protesters looted stores and vandalized cars in a confrontation with police.

The mayor said a small group caused the trouble; 32 people were arrested.

Charlie Dooley is the county's executive.

CHARLIE DOOLEY, Saint Louis County Executive: We're on top of this situation. We understand their frustration. We understand their concern. We are asking that all the public be calm, be patient and be prayerful.

JEFFREY BROWN: Another vigil and protest march were held today.

And Brown's parents spoke at a news conference.

LESLEY MCSPADDEN, Victim's mother: That's my firstborn son. Anybody that know me knew how I felt about my son. I just wish I could have been there to help him, anything. He didn't deserve that.

JEFFREY BROWN: And the FBI confirmed it is reviewing the shooting for possible civil rights violations.

It's the latest such case since the fatal shooting of Trayvon Martin in 2012 by a neighborhood watch member in Florida. Last month, in New York City, another black man, Eric Garner, died after being put in a chokehold by police, according to a medical examiner.

And in Los Angeles, onlookers videotaped Marlene Pinnock as she was beaten by a California Highway Patrol officer.

We get reaction now from Sherrilyn Ifill, president of the NAACP's Legal Defense Fund, and Greg Meyer, a former captain for the Los Angeles Police Department who's written on and testified in use-of-force cases around the country.

Well, Sherrilyn Ifill, let me start with you. It's still early in this investigation. What do you think are the most important facts to learn and who is best to determine them?

SHERRILYN IFILL, NAACP Legal Defense and Educational Fund: Well, I think would be terrific if we learned the name of the officer and something about his record on the force, obviously the eyewitness accounts — and they are conflicting eyewitness accounts — between residents of the community who say they observed what happened, and what we are hearing from the police department.

We don't know the name of the officer or anything about him. I think we're entitled to know that. He is a public servant. And so we're going to know what happened during that encounter between Mike Wood (sic) and the police.

Frankly, the account that we have heard about this struggle for the gun is all too familiar and, frankly, raises a lot of questions. And so we need an investigation to happen. I'm pleased that the FBI has joined — they have not taken over — it's a concurrent investigation.

But we need an investigation to happen quickly. And we need answers quickly. We are still waiting for charges in the Eric Garner case. And I think these are the kinds of things that are creating frustration within communities around the country.

JEFFREY BROWN: Let me ask Greg Meyer.

From a police perspective, when you have these kinds of questions over use of deadly force, what has to come out? What are the important facts that you want to see brought out?

GREG MEYER, Former Captain, Los Angeles Police Department: Well, first of all, the investigations tend not to happen quickly. They tend to be very thorough and they take some time.

What has to happen here is a realization that this officer was in this situation. You're going to get that officer's statement. You're going to get witness statements. I'm not aware that there is any video or audio evidence in this case.

If there is, all of that would be part of what's analyzed too. Ultimately, the system will decide, through policy review, training review and legal review, was this officer's actions reasonable under the Constitution of the United States? We're not going to know for some time how to evaluate that.

And I would just add briefly, about 10 percent of all officers that are murdered in this country each year in modern times are murdered with their own handgun. That's down from 20 percent a generation ago, because I think we're getting better at retaining our weapons.

But the struggle over the gun is a big question in this case that will have to be answered.

JEFFREY BROWN: Well, Sherrilyn Ifill, you can respond to that and I want you to pick up on where you ended. What — we saw the strong response in the community and nationwide. Tell us where that's coming from.

SHERRILYN IFILL: Well, I think there is a local response that has to do with the relationship between the African-American community and the constabulary in Ferguson, which I think bears some investigation as well.

If you look at the statistics involving arrests, stops and so forth in that town prepared by their police department, African-Americans are the subject of 90 percent of the stops, whether in vehicles, whether on the street, whether on local roads, whether on the highway.

And, interestingly, however, the greatest amount of contraband that's found happens with stops of white residents. So I think there may be a local story that needs to come out. But there's also a national story. You just alluded to several of the incidents. I talked about Eric Garner.

We know that a man was killed in the Wal-Mart in Ohio last week by police officers who was unarmed. We saw the disgusting video of Ms. Pinnock being brutally beaten on a highway by a California police officer. And that's just in the last few months. These incident goes back decades.

We could rattle off names and use up the entire NewsHour doing so of cases of police-involved attacks, shootings, assaults on unarmed African-Americans. And so I think the larger issue is about the way in which the police force in cities all over this country engage with unarmed, nonviolent African-Americans, the perception of criminality when African-Americans are seen, and the often violent and disproportionately violent response of police officers who are trained and should be trained public servants, trained in defusing situations.

The gun should be the last resort, and, too often, we see it as the first resort.

JEFFREY BROWN: Well, let me ask Greg Meyer.

Do you sense that police forces around the country see cases like this as part of a systemic problem? And to what extent are they responding to it and retraining to respond?

GREG MEYER: Well, I think every incident is different, whether it's an African-American person involved or not.

There's more and more training going on, and more and more training programs being developed on, for example, how to handle mentally ill people. There's more and more court oversight. I know in the Ninth Circuit out in the Western United States, the federal Ninth Circuit Court of Appeals has issued at least one opinion where they're looking not just at the moment that force was used, as was what was traditionally looked at, but also what's leading up to it.

What tactics are the officers engaging in before they go in and use force on someone? So it's an evolving issue. We're going to see more and more videos.

GREG MEYER: I mean, police officers have videos on their bodies in many cities now. That's only going to increase, in addition to all the other videos that we know are out there.

JEFFREY BROWN: Just very briefly, in our last minute, Mr. Meyer, do you sense, though, that police forces understand the anger that this quickly arouses in communities around the country?

GREG MEYER: Oh, sure, especially in the big places, New York, Los Angeles, other big cities.

These things happen with more frequency than they do in the smaller jurisdictions, for sure. So, the police officers get some experience with understanding the frustration that's out there, the anger that's out there. Videos especially drive people emotionally. And we're a nation of laws, not emotion.

JEFFREY BROWN: OK.

And, Sherrilyn Ifill, just in 20 seconds, please, a last — a last word?

SHERRILYN IFILL: Dead children actually drive people emotionally even more than videos, people who are unarmed, watching a man be choked to death on nationwide television who clearly is unarmed.

Those things actually arouse, and appropriately arouse, emotion. And they shouldn't arouse the emotions just of African-Americans, but of every American. We are a nation of laws. And we want police officers to be accountable to the law, just as the citizenry should be as well.

GREG MEYER: Absolutely.

JEFFREY BROWN: All right, Sherrilyn — Sherrilyn Ifill and Greg Meyer, thank you both very much.