NORTH CHARLESTON, S.C.

Four bullets to the back and one in the ear.

That’s the unimaginable pain an unarmed Walter L. Scott suffered as he was fatally gunned down by white police officer Michael T. Slager as he ran away following a routine traffic stop.

The gruesome slaying was graphically recorded on the cellphone of a bystander Saturday morning in North Charleston, S.C.

It is the latest in a string of highly publicized incidents across the nation — including Ferguson, Mo., New York City and Cleveland, Ohio — in which white police officers have killed unarmed black men. Each instance raises questions — and public consciousness — about disparate treatment by people of color by police and racial injustice in the United States.

Mr. Slager was charged with murder Tuesday and fired from the police department after the video surfaced. He is being held without bond. If convicted, he could receive the death penalty or life in prison.

He was arrested by the South Carolina Law Enforcement Division, the agency investigating the shooting. The FBI and U.S. Justice Department also are investigating.

Demonstrators peacefully rallied Wednesday in North Charleston to express their outrage. They held signs that read “Back Turned, Don’t Shoot,” “Black Lives Matter,” “The Whole World Is Watching” and “We Are All Human.”

Civil rights leaders have called for calm, and many people praised the courage of the witness who filmed the officer shooting Mr. Scott. The witness gave the video to Mr. Scott’s family.

“When I saw it, I fell to my feet and my heart was broken,” Mr. Scott’s father, Walter Scott Sr., said on NBC’s “Today” show on Wednesday. He said the officer “looked like he was trying to kill a deer running through the woods.”

Without the video, he said, “it would have never come to light. They would have swept it under the rug, like they did with so many others.”

The video shows Mr. Slager, 33, without hesitation, shooting eight times at the 50-year-old Mr. Scott as he ran away after being stopped by Mr. Slager for a broken brake light.

Five of the bullets struck him, Chris Stewart, an attorney for the victim’s family, said.

Mr. Scott then slumps down to the grass.

According to a police report, Mr. Slager told other officers that Mr. Scott had taken his stun gun during a brief scuffle.

At no point in the video, which does not show the initial contact between the men, does Mr. Scott appear to be armed.

Without attempting to provide any life-saving aid, the officer is seen placing the victim in handcuffs as he lies on the ground. The officer then walks back to a spot near where he opened fire.

The video then shows him appearing to pick something up, returning to Mr. Scott and then dropping it on the ground next to Mr. Scott, apparently to stage the scene to match his description.

Mr. Stewart said Tuesday night that the incident is bigger than race.

“It goes to power itself. This was a cop who felt like he could just get away with shooting someone that many times in the back,” Mr. Stewart said. “It speaks to the value of human life.”

The Rev. Al Sharpton, head of the National Action Network, decried the savage killing and called for prompt action to stem the tide of incidents of police brutality against black men.

“When a black man is stopped for a broken tail light and ends up being shot multiple times in the back, it is yet another reminder that we need a national strategy to implement real and meaningful police reform now,” he stated. “We simply can’t rely on citizens with video cameras to make sure justice is served.

“We know that the majority of police officers are fair and just public servants,” Rev. Sharpton continued. “But the events of the past year show we still have a long way to go to ensure every citizen in America is treated equally in the eyes of law enforcement. The time to act is now.”

North Charleston Police Chief Eddie Driggers said he viewed the video. “And I was sickened by what I saw. And I have not watched it since.”

North Charleston Mayor Keith Summey told reporters that Mr. Slager must be held accountable for his actions. He said the remainder of the police force in North Charleston soon will be equipped with body cameras.

Mr. Scott was a father of four and had just proposed to his longtime girlfriend a week before his death, according to his family. He served two years in the Coast Guard.

Family members have described him as a loving, kind and caring family man who enjoyed sports, particularly the Dallas Cowboys.

The victim’s family plans to file a lawsuit against Mr. Slager, the police department and the city alleging that his civil rights were violated, Mr. Stewart said.

North Charleston is home to about 100,000 people, nearly half of whom are black, 2010 U.S. Census data show.

By contrast, only about 18 percent of its police department’s roughly 340 officers are black, The Post and Courier, a local newspaper, reported last year.

Mr. Scott’s arrest history, mostly for contempt of court charges for failing to pay child support, included one accusation of a violation stemming from an assault and battery charge in 1987, the newspaper reported.

Mr. Slager, also formerly a member of the Coast Guard, had not previously been disciplined by the department, The Post and Courier said. He has two stepchildren and a wife who is eight months pregnant. The mayor said that, despite her husband’s firing, she would still be covered by city health insurance.

The paper reported that, in 2013, a man accused Mr. Slager of shooting him with a stun gun without cause, but that Mr. Slager was cleared of wrongdoing by an internal police investigation.

Richmond has remained mostly free in recent years of incidents of officer-involved shootings of black men.

However, last week, an officer shot a 29-year-old black man outside a Midlothian Turnpike hotel after the man allegedly pointed a gun at the officer during a foot pursuit. The investigation into the shooting is ongoing.