Salt Lake City police confirmed one officer, and possibly a second officer, were involved in the shooting, but did not provide more details.
There was conflicting information about the boy's age. Hansen said that he was not 16, but older. Hansen said more details would be released later Sunday.
Salt Lake City police later said in a tweet that officers were responding to a call in area when they were alerted to assault in progress.
The officers "tried to engage altercation," the tweet added.
After the shooting, Salt Lake Tribune journalists saw and heard onlookers yelling obscenities at police and throwing rocks.
There were "a lot of hostile people upset about what had taken place," Detective Greg Wilking said.
Police detained multiple people, but Wilking could not elaborate on why.
According to Mohammad, the victim and a man were in a confrontation, and the victim was holding part of a broomstick at his side when officers ran up.
"They told him to put it down, once," Mohammad said, and "started shooting him as soon as he turned around."
Mohammad said that the teenager was hit in the chest and stomach.
Neighboring departments, including Unified Police Department, West Valley City, Sandy and University of Utah police, deployed to assist Salt Lake City officers. In all, almost 100 officers, some carrying riot shields, arrived.
Hansen said one officer was hit with a bottle, but he did not have details about whether that officer or any other was injured.
At 8:40 p.m., a line of officers moved people down the sidewalk on the south side of 200 South, from Rio Grande to 400 West.
Police closed the Trax Blue Line before the Old Greektown stop, providing difficulties for some fans leaving the Utah Jazz game. The TRAX trains resumed about 11 p.m.