Police Chief Charlie Beck told The Times that he and Mayor Eric Garcetti spoke at length about the issue and chose to release the video to correct what the chief described as competing accounts about Saturday's shooting.
Commission president Matt Johnson said releasing the video was in the public's best interest, but warned it was too early to determine whether the shooting was justified or not.
It shows a man in gray sweat trousers and a purple hooded sweatshirt running through a strip mall parking lot before taking cover behind a sports utility vehicle with what appears to be handgun in his left hand.
Snell then reportedly jumped out of the auto, prompting a foot pursuit by police.
Beck said on Monday that Carnell Snell, Jr., 18, turned toward officers with the gun before he was shot. In the footage, a man wearing a purple hoodie and light-colored sweat trousers is seen running through a parking lot toward the front of a strip mall.
The release of the video marked the latest example of police departments that have chose to release footage of deadly confrontations amid public pressure. The gun was loaded with one round in the chamber, Beck said.
A lawyer says a lawsuit is planned over the death of a black man after he was restrained by police in Pasadena, California.
Corey Feldman returns to Today for another test of America's character
Only time will tell whether we pass this test, or if Today just has to keep bringing him back until we do. They were like, "Oh, my God, we did it!" And then I get on the plane and I immediately start sobbing.
The video, which Beck said he released after consultation with Mayor Eric Garcetti and the District Attorney's Office, shows Carnell Snell Jr running with his left hand in a sweatshirt pocket, and at one point he removes his hand to reveal a handgun.
Rowdy protesters blocked an intersection as they marched in Los Angeles streets for a second night over the deadly police shooting of an 18-year-old black man. Beck said a man, later identified as Snell, exited the auto when it slowed down. A woman who witnessed the shooting told KTLA that the victim "had his hands to the side when they jumped out and they didn't say nothing". Protesters had demanded the release of the video. He holds the gun at his side briefly, then tucks it in his waistband, turns and runs away from the camera, out of sight, with officers in pursuit.
The release of the tape came as the LAPD worked to quell protests sparked by the death of the black suspect, who was shot on 107th Street Saturday afternoon. Officers believed the vehicle was stolen, according to Beck.
Officers said they began pursuing Snell Saturday after they tried to pull over a auto he was in, because it had paper plates that didn't match the year of the vehicle - a possible indication of a stolen auto and something commonly seen in drive-by shootings, according to Beck. Police fatally shot Scott after they say he refused commands to put down a gun. Last Tuesday, police in San Diego suburb of El Cajon shot dead Alfred Olango when he pointed at an officer what turned out to be an electronic cigarette device.
Several protesters interrupted Beck on Tuesday as he appeared before the city's police commission, with some shouting "fire Charlie Beck" and others holding up signs that read "Hands Up, Don't Shoot".
Beck said a semi-automatic handgun found next to Snell's body was fully loaded.
In Snell's South Los Angeles neighborhood of small stucco houses and well-kept lawns there was a makeshift shrine of flowers and candles in front of the property where he died.