WASHINGTON: A video of the dying moments of a black man shot by Minnesota police after being pulled over while driving went viral on Thursday, a day after a video emerged of a similar incident in Louisiana.

"Oh my God, please don't tell me he's dead, please don't tell me my boyfriend just went like that... You shot four bullets into him, sir," a woman, identified on her Facebook page as Lavish Reynolds, is heard saying in the video shot on her camera phone.

Police confirmed the shooting by an officer. Family and activists identified the victim as school cafeteria worker Philando Castile, 32.

Castile can be seen in the driver seat, large blood stains spreading through his white shirt. Reynolds sat next to him and her young daughter was also traveling in the car.

Series of shootings

The shooting took place just one day after police in Louisiana shot dead a black father of five at point-blank range, in a incident being probed by federal investigators.

The shootings came on the eve of a closely watched trial in Baltimore on Thursday of an officer charged in the death of Freddie Gray, a black man who suffered a broken spine in the back of a police van.

In the video of the Minnesota killing, broadcast on Facebook Live and already viewed more than 1.7 million times, Reynolds says the car was pulled over for a broken tail light. She later says there was also marijuana in the car.

Castile had a legal license to carry a firearm and was reaching for his license and vehicle registration when police shot him, she adds.

Police said the incident was being investigated and a handgun was recovered at the scene.

Castile "was trying to get out his ID and his wallet out of his pocket, and he let the officer know that he had a firearm and he was reaching for his wallet, and the officer just shot him in his arm. He just shot his arm off," Reynolds says in the video.

She says the police officer, who has not yet been identified, was "Chinese."

With Castile moaning and gasping for air, the police officer pointed his gun through the car window.

"I told him not to reach for it! I told him to get his hands up!" the officer shouted.

For much of the nearly 10-minute video, Reynolds can be heard wailing, off and on camera, as police apparently cast her phone to the side at one point and later handcuffed her, so she could not hold the phone up.

A Facebook page set up by supporters, Justice for Philando Castile, said: "Philando Castile was murdered by police on 7/6/2016. We demand justice!"

'It's ok, mommy'

In a poignant moment toward the end of the video, Reynolds's four-year-old daughter can be heard reassuring her deeply distraught mother.

"It's ok, mommy," says the girl sweetly. "It's ok, I'm right here with you."

Activists said the girl was just four years old.