Charleston - A man who recorded chilling video of a white police officer gunning down a black man said on Wednesday that the shooting followed a struggle in which the cop had gained control of the situation.The now widely-distributed video of South Carolina officer Michael Slager shooting Walter Scott repeatedly in the back was recorded by 23-year-old Feidin Santana.The video sparked public outcry and led to a murder charge against the policeman after it challenged the officer's account of the shooting that took place in the coastal city of North Charleston.The shooting is America's latest high-profile police killing of a black man. A string of such shootings of unarmed victims, where officers are rarely charged, have sparked protests around the country with demonstrators alleging racism in the nation's police forces."Before I started recording, they were down on the floor. I remember the police [officer] had control of the situation," Santana said in an interview with NBC television about what he witnessed in the moments before filming started."He had control of Scott. And Scott was trying just to get away from the Taser [stun gun].""I knew right away, I had something on my hands," he said about recording the video.Murder chargeSlager was arrested and charged with murder after the video surfaced showing him shooting eight times at Scott, 50, while Scott was running away.He was fired from the police force on Wednesday after being charged with murder and being booked into jail.Slager could face a sentence of up to life in prison or the death penalty.Mayor Keith Summey announced the sacking at a highly-charged press conference frequently interrupted by residents angered over the killing.The mayor said the police department would buy body cameras for officers to wear to help investigate shootings.Protesters gathered in front of City Hall throughout the day on Wednesday and demonstrated against racial inequality.Signs at the rally included slogans such as: "Stop racist police terror," and "No justice, no peace,"Some demonstrators said the quick arrest of the officer helped defuse what could have been a tense situation.Chilling videoThe deadly shooting occurred Saturday following a traffic stop for a broken tail light. After initial police reports claimed Scott had taken Slager's stun gun, Santana's video was released to The New York Times and published Tuesday.The video shows wires from the stun gun extending from Scott's body, implying that the victim rather than the police officer had been hit as the two men scuffled.As Scott, who was heavy-set, tries to flee, Slager draws his handgun and shoots eight times toward his back.The officer later approaches Scott, who is on the ground, telling him to put his hands behind his back, before putting him in handcuffs.Slager appears to pick up a device that had fallen during the altercation and drop it by Scott's body.Scott was hit by five bullets - three times in the back, once in the upper buttocks and once in the ear, said family lawyer Chris Stewart, quoting the coroner who examined Scott's body, according to the Times.Community reactsScott's father, also named Walter, said the family was devastated by his son's death, but was grateful for the video evidence."The way he was shooting that gun, it looked like he was trying to kill a deer or something running through the woods. I don't know whether it was racial or something wrong with his head or what," the father told NBC's Today Show."I thank God they had the video. God has my back. When I saw it, my heart was broken. I said, 'It can't be.' I saw it. I couldn't take it anymore."The victim's family spoke out at a news conference after the officer's arrest and called the unidentified person who filmed the video a hero.They remembered Scott as a Dallas Cowboys football fan and loving father of four.Senator Lindsey Graham of South Carolina expressed his dismay after seeing the video."The horrific video is very difficult to watch and deeply troubling on many fronts," Graham said.The US Justice Department released a statement saying it would "take appropriate action" over the shooting.A string of shootingsThe killing of unarmed black teen Michael Brown in August was a catalyst for a recent surge in protests and a renewed debate on racism and police tactics.A jury chose not to indict a Ferguson, Missouri, police officer for the shooting. Since then, other killings by police have prompted protests in cities from coast to coast.In December, two New York police officers were killed by a gunman who had boasted he was going to avenge police abuses.Police officers have enjoyed significant legal leeway in the United States and prosecutors and civilian grand juries have often proved reluctant to indict them over excessive force.The US Justice Department has launched investigations into a number of police departments after shootings.It unearthed what it called damning evidence of racism in the Ferguson police force after Brown's shooting.