Angry protests erupted in Salt Lake City overnight following a police-involved shooting, according to authorities.
Salt Lake City Police said the shooting occurred after officers responded to reports of an assault in progress and tried to intervene in the altercation.
Detective Greg Wilkeng said two officers were involved but it was not yet clear which had fired or how many shots were discharged.
Police did not identify the victim or release information about his age or condition.
Wilken said the altercation took place at around 8 p.m. local time, and the officer on the scene called for all hands on deck because the scene quickly turned hostile after the shooting.
Angry people congregated on the street shouting, "They shot an innocent kid," and objects were hurled at police officers, witnesses told NBC station KSL.
In audio published by the online archive service Broadcastify, a male officer is heard requesting "a bunch of units" come "quickly" to help push back the crowd.
"Let's get them off this street... and get medical in here," a voice says.
An officer warns "be advised, they are throwing bigger rocks" and later "we need more units... there is glass and other items being thrown."
There were preliminary reports that officers were injured by thrown objects, but Wilkeng said he could not confirm that information.
"It is still quite volatile here," Wilkeng told a news conference.
He said witnesses have been brought to police headquarters to give statements and urged members of the public with cellphone video of the incident to come forward.
This article originally appeared on NBCNews.com.