Video shows the moments before North Miami police inexplicably shot an unarmed black carer.

A video has emerged of an unarmed black carer lying down on the street with his hands in the air, capturing the moments before local police inexplicably shot him.

When he was shot, Charles Kinsey was lying beside the 23-year-old autistic man he cares for, who had run away from a North Miami mental health facility.

Neal Cuevas, the North Miami Assistant Police Chief, told The Miami Herald police responded to an emergency call on Monday that a man was threatening to kill himself in the middle of a road.

When officers arrived they found Charles sitting with the mentally disabled man, who was not in possession of a gun but instead playing with a toy truck. Charles was unthreatening, simply trying to coax his patient, Rinaldo, into returning to the facility.

Upon arrival, police demanded the pair lie on the ground and put their arms in the air.

While Charles did just that, Rinaldo stayed seated.

Horrified onlookers pulled out their phones to capture the footage from the periphery. In the video, Charles can be heard pleading with police.

“All he has is a toy truck. A toy truck. I am a behaviour therapist at a group home.” The carer can also be heard pleading with Rinaldo to follow police instructions. “Rinaldo, please be still, Rinaldo. Sit down, Rinaldo. Lay on your stomach.”

Then, for no obvious reason at all, police fired three shots at Charles, one hitting him in the leg.

"When I went to the ground, I’m going to the ground just like this here with my hands up," Charles since told WSVN-TV from his hospital bed.

"I am laying down here just like this, and I’m telling them again, ‘Sir, there is no need for firearms. I’m unarmed, he’s an autistic guy. He got a toy truck in his hand.”

"When he shot me, it was so surprising.”

“It was like a mosquito bite, and when it hit me, I’m like, ‘I still got my hands in the air, and I said, ‘No I just got shot! And I’m saying, ‘Sir, why did you shoot me?’ and his words to me, he said, ‘I don’t know'."

After police shot him, they turned him face-down on the asphalt, patted him down and placed him in handcuffs.

While North Miami police have not released the officer's name, they say an investigation into the incident is ongoing.

In the US, the prevalence of police brutality towards black people is alarming. While black deaths at the hands of police are frequent, the unexplained shootings of Alton Sterling - a father and salesman -  and Philando Castile earlier this month sparked outrage worldwide, and prompted a resurgence of the #BlackLivesMatter social media movement.