The family of a young black man whose fatal shooting by a traffic officer was live streamed on video, have accused police of “executing” African American men across the country.

Valerie Castile, the mother of Philando Castile, said she had watched the video of her son being shot on Wednesday night and was outraged. She said young black men and women were being shot by the very people who had taken an oath to protect them.

“We know black people are getting killed. I told [my children] that whatever you do [if you get pulled over by police and told to do something] comply, comply, comply,” she said on CNN.

The killing of Mr Castile, 32, who was shot after being pulled over in Falcon Heights, Minnesota, came just hours after the US Justice Department opened an investigation into the shooting of a black man, Alton Sterling, by police in Baton Rouge, Louisiana on Tuesday.

The incidents are the latest in a string of fatal encounters between police officers – usually white – and black or minority suspects, that have sparked outrage and protests across the country. Campaigners have called for an overhaul of the entire justice system, saying the repeated incidents prove the problem is not simply the result of one or two “bad apples”.

Philando Castile was shot dead on Wednesday night in Minnesota (Family)

Such incidents have gained national attention largely as the result of the ubiquity of mobile phones with video capability. As a result, a handful of police officers have been prosecuted for incidents that may previously have escaped such attention.

Yet the video captured of Mr Castile’s death is remarkable, even in an nation where gruesome evidence has become commonplace, because it was live streamed and his fiancee, Lavish Reynolds, narrated what was happening around her. Her four-year-old daughter was present when the shooting took place.

Falcon Heights shooting

“You shot four bullets in him, sir. He was just getting his licence and registration, sir,” Ms Reynolds is heard to say, as she sits in the passenger seat of a car. Later she adds: “Oh my God, please don't tell me he's dead. Oh my God, officer have you just killed my boyfriend.”

Mr Castile’s family said they were grateful that Ms Reynolds had been able to film the incident otherwise they would not have known what had happened. "These things are happening because there are no checks and balances in the justice system. African Americans are being executed by the police," said Ms Castile.

She said that her son and his sister were licensed to carry weapons. Yet she said her daughter had told her recently that she was scared to carry her weapon as she feared she lived in a country where police “shot first and asked questions later”.

A statement from the St Anthony Police Department said an unidentified black man was wounded during a traffic stop in Falcon Heights, Minnesota, at 9pm. He was taken to a hospital, where he later died.

Ms Reynolds can be heard saying on the video that boyfriend had just been pulled over for a having a broken tail light and explained that he had a gun he was licensed to carry.

“He was trying to get out his ID and his wallet out of his pocket,” she said. “He let the officer know that he had a firearm and that he was reaching for his wallet, and the officer just shot him in his arm.”

One man, who is not identified, is heard saying: “F***. I told him not to reach for it.”

Police said a handgun was recovered at the scene and that the state Bureau of Criminal Apprehension was investigating the incident.