Salt Lake District Attorney Sim Gill released the body-cam footage to the public Monday, after it was shown in court during Mohamed's preliminary hearing on robbery and drug charges.
Matt Romrell, of Utah Against Police Brutality, said that when the group saw the video, "jaws hit the floor."
During a rally Tuesday night at the city's public safety building, activists such as Lex Scott called for the charges against Mohamed to be dropped.
"I don't care what crimes Abdi was [allegedly] committing. They didn't try any de-escalating tactics," said the activist, a member of the United Front and Community Activist Group organizations.
Ian De Oliveira, with Utah Against Police Brutality, said the footage doesn't match the account they'd been given by Gill; the activist said deadly force was used too soon, rather than as an "absolute last resort."
"We see it from the point at which they're across the street, and the first thing they do is pull out the gun," said De Oliveira.
Ian Adams, executive director of the Utah Fraternal Order of Police, said earlier Tuesday that the video footage shows that the shooting was a "totally, legally justified shooting."
He said Checketts and Winegar acted heroically.
"They are down there, responding to a totally separate complaint," Adams said. "They're not expecting to be involved [in a shooting] 30 seconds later. But one of the officers, his attention is called to an aggravated assault and they immediately both rush to assist that victim. That's what I mean by heroism."
The body cameras show the officers spotting the altercation involving Mohamed, an unidentified man and Kelly McRae. The police run and yell at Mohamed to drop the metal broom handle he is carrying.
About 15 seconds later, shots are fired.
In the video, Mohamed does not appear to react to the officers. Instead, he walks toward McRae with the broom handle in his hand as McRae backs up, his hands in the air.
Adams he found it significant that everyone but Mohamed reacted to the officers running toward them and yelling.
"It stood out to me that everybody in the area hears what those officers are saying," he said. "Mr. Mohamed is clearly so intent on assaulting that victim. If he's simply choosing not to hear them or he's just so locked in to his violent ways that he doesn't hear them either way, the fact is that everyone else, including one of the other suspects, responds. That tells me Mr. Mohamed had every chance to surrender in a peaceful way and just didn't."
After the shooting, the teen lay bleeding on the ground for at least five minutes without receiving first aid. The video shows a crowd of people gathering near the teen and yelling as the two officers holler at the crowd to get back.
De Oliveira was critical of that development, saying Tuesday night that the footage shows responding officers standing around and discussing the crime scene while leaving Mohamed without medical care. Four and a half minutes into the video, officers put on gloves and appear to search the body.
"Obviously it was secure enough to go through his pockets, but it wasn't secure enough to try to put pressure on the wound, try to stop the bleeding, try to save this person's life," said De Oliveira.
The police officers' No. 1 priority after a shooting, Adams said earlier Tuesday, is to secure the scene as firefighters and paramedics arrive something the two officers could not do quickly because of the crowd that had gathered around them. People can be heard in the videos, screaming at the officers, some saying Mohamed needed help, others asking why the officers fired, while others swear at the officers and call them names.
"You can see in the video just how chaotic it is," Adams said. "There's two of these officers and hundreds of people and witnesses and uninvolved parties some of which are clearly not friendly towards them. ... In order to safely render first aid, that means getting down with [their] backs turned to people who clearly have hostile intent towards them."
People also threw rocks and bottles at police.
Mohamed was charged in juvenile court with aggravated-robbery and drug-distribution counts. At a hearing next month, a judge will decide whether the case remains in the juvenile system or is moved to the adult court system.