Gov. Mark Dayton of Minnesota on Thursday asked the Department of Justice to investigate the killing of a black motorist shot by a white police officer. Philando Castile's dying moments were live-streamed on Facebook, and the incident prompted a comment from President Barack Obama.

Dayton said he wanted an "immediate independent federal investigation into this matter." The governor suggested that racism was to blame for the killing of Castile, a 32-year-old school cafeteria manager, who was shot at least four times by a police officer after being pulled over for a broken taillight in Falcon Heights.

"Would this have happened if those passengers, the driver and the passengers, were white?," Dayton told a news conference Thursday. "I don’t think it would have. So I’m forced to confront, and I think all of us in Minnesota are forced to confront, that this kind of racism exists."

He continued:

"Nobody should be shot and killed ... for a taillight being out of function," the governor said. "Nobody should be shot and killed while seated still in their car. I'm heartbroken."

Without the video, the Wednesday shooting likely would have received scant attention from the media, government officials, and the public. There were public protests in the suburban St. Paul town where the man was killed, and elsewhere.

The dead man's girlfriend, passenger Diamond Reynolds, used her mobile phone to film the gruesome aftermath of the shooting, and it was streamed on Facebook. Castile is seen soaked in blood in the driver's side, shot as many as four times.

The "police shot him for no apparent reason, no reason at all," the woman is overheard saying in the video.

President Obama also weighed in Thursday afternoon, saying in a Facebook statement that all Americans should feel “deeply troubled” by the Castile shooting and the recent police shooting of Alton Sterling in Baton Rouge, La.

Reynolds, the passenger, is overheard on the video saying that the St. Paul suburban police officer, whose name was not released, asked Castile for his driver's license and registration. According to the video, after the man is shot multiple times, the passenger told the officer "that it was in his wallet, but he had a pistol on him because he's licensed to carry."

"The officer said, 'Don’t move.' As he was putting his hands back up, the officer shot him in the arm four or five times," the passenger said in the video.

After the shooting, the officer is then overheard on the video yelling, "I told him not to reach for it. I told him to get his hand out."