Note: This video is graphic and may be disturbing to some viewers.

Chicago officials on Tuesday evening released dash cam video from the 2014 incident in which a police officer shot teenager Laquan McDonald 16 times.

Cook County State’s Attorney Anita Alvarez described the video footage as “chilling” during a news conference hours before the footage was released.

“I have no doubt this video will tear at the hearts of all Chicagoans,” Alvarez said.

In the video, McDonald is carrying with a small knife and walking away from officers, Alvarez said. Chicago police officer Jason Van Dyke opens fire as he stands about 10 feet away, and keeps shooting for roughly 13 to 15 seconds even after the teen falls to the ground.

Shortly after police released the video Tuesday, the site hosting it crashed.

Tuesday morning, Alvarez’s office brought a first-degree murder charge against Van Dyke, who could face 20 years to life in prison if convicted.

“Every day in this city, you see thousands of officers performing admirably,” Chicago Police Superintendent Garry McCarthy said in a press conference for the video’s release. “The officer in this case took a young man’s life, and he’s going to have to account for his actions.”

For more than a year, community members have urged officials to release video of the shooting that ended the 17-year-old’s life. The city was forced to act after a judge issued a court order to release the video before 3 p.m. Wednesday.

McDonald’s family, which received a $5 million settlement from the city, did not want the video released, but said they understood the decision.

“We deeply appreciated the outpouring of love and support for Laquan,” the family said in a statement through their attorneys. “While we would prefer the video not be released, we understand a court has ordered otherwise.”

They family has also appealed for calm, urging that those who view the video “don’t resort to violence in Laquan’s name.”