WARNING: Graphic video below.

A police officer shot and killed a black man in St. Paul, Minnesota on Wednesday night during a routine traffic stop, the aftermath of which was captured on video and streamed on Facebook by his girlfriend sitting in the front seat.

This was the second fatal shooting of a black man by police officers in less than two days. The Minnesota shooting came hours after the Justice Department said they were opening an investigation into the killing of a black man in Baton Rouge, Louisiana, on Tuesday by two police officers.

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

Relatives identified the man as Philando Castile, 32 who worked in the cafeteria of a St. Paul school, reported the Minneapolis Star Tribune.

A woman sitting in the front seat of the car recorded the aftermath of the shooting in a 10-minute long video that quickly went viral after she posted it on YouTube and Facebook.

The graphic video shows a man, covered in blood, slumped in the front seat of the car as his self-identified girlfriend sits next to him and calmly describes what just happened.

"Please, officer, don't tell me that you just did this to him," she said to the cop, who was still aiming his gun into the window of the car. "You shot four bullets into him, sir. He was just getting his license and registration, sir."

The woman went on to explain that police shot her boyfriend several times after they had been pulled over for a broken taillight. Her boyfriend had a license to carry a firearm, which he told the cops, she said in the video, and he was reaching for his documents when he was shot in the arm.

"Fuck," a panicked man is heard screaming in the video, who appears to be the police officer. "I told him not to reach for it."

"He doesn't deserve this," the woman said in the video, crying. "He was a good man."

In the backseat of the car was the woman's daughter, who can be heard at several points in the background. Toward the end of the video, the young girl can be heard comforting her mother, saying "It's O.K., Mommy. It's O.K. I'm right here with you."

Soon after the video circulated online, protesters gathered outside the governor's mansion in St. Paul.

Police confirmed the shooting Wednesday night and said the officer involved was placed on paid administrative leave.

Castile's sister called the incident a "modern day lynching," as she gathered with other grieving relatives outside the hospital where he died.

"It's just like we're animals. It's basically modern-day lynching that we're seeing going on, except we're not getting hung by a tree anymore — we're getting killed on camera," his sister, Alize Castile, told CBS News.

Later in the video the woman can be heard saying, "Oh, my God, please don't tell me he's gone. Please don't tell me my boyfriend just went like that."