32-year-old Philando Castille was fatally shot by police on Wednesday night in St Paul, Minnesota during a traffic stop. 

Speaking on Thursday, just hours after the death of her son, Castille's mother Valerie said that both Philando and her daughter had expressed concern over carrying their weapons despite having permits for them, as she was afraid that "they'll shoot me first and ask questions later." 

In the wake of his shooting, the passenger in the car, Diamond Reynolds, filmed and live-streamed a video on social media, which has since gone viral. 

Asked what he saw when he watched the video, Philando's uncle Clarence said: "I saw my nephew shot by a man, clinging to his life, with no help. It was the most horrific thing I've ever seen in my life."

Both expressed their thanks to Diamond for streaming the video, stating that "we never would know exactly what happened had she not put that out there like that."

Valerie emphasised that she had always told her son to comply when stopped by the police, but that even that no longer seems to be enough:

"That's the key thing — the key thing in order to try to survive being stopped by the police, is to comply. Whatever they ask you to do, do it. Don't say nothing. Just do whatever they want you to do. So what's the difference in complying, and you get killed anyway?"

Castille's death comes comes only days after Alton Sterling's death was filmed on the mobile phone of onlooker and activist Arthur Reed, who was just metres away as two white police officers tried to arrest the 37-year-old.

Mr Sterling, a father of five who had been arrested a number of times before, had been selling CDs outside a convenience store in Baton Rouge, Louisiana.