St. Louis police shot and killed 18-year-old Mansur Ball-Bey after the man allegedly turned and aimed a gun at the officers as they were executing a search warrant on Wednesday. Protests broke out at the scene of the shooting shortly thereafter, drawing about 100 people to the north St. Louis area. Police deployed tear gas and arrested nine people, authorities said.

Ball-Bey and another unidentified man were attempting to exit the back entrance of a home when police entered to conduct a search, St. Louis Police Chief Sam Dotson said at a press conference. Both men were allegedly carrying firearms, and as they ran away from the scene, Ball-Bey reportedly pointed his gun at the police; two officers opened fire, killing the man.

Both officers were placed on administrative leave following the shooting. The other suspect escaped and remains at-large, according to a statement released by the St. Louis Metropolitan Police Department on Wednesday. Four guns were recovered at the residence, including three that were reported stolen.

A group of protestors took to the area and blocked traffic, prompting police to make arrests.

"[P]eople moved to the sidewalk and peace was restored," Dotson told reporters. "As officers left the area, the group came back into the street. Just as officers were about to respond to make a few additional arrests, the group started to march."

About 100 protestors marched along the street and ultimately blocked traffic at the intersection of Page and Walton, where police ordered the group to disperse. Dotson cited reports that glass bottles and bricks were thrown at the officers, who used shields to protect themselves, adding that video of the violence would be released. Footage of the scene has already been circulating online, with several showing protestors tossing plastic water bottles near patrol cars where officers were stationed.

In one video taken by police and uploaded to YouTube on Thursday morning, protestors are seen hurling rocks, bricks, and water bottles at the officers.

The officers first deployed smoke canisters in an effort to control the situation. "After that didn't have any effect with the crowd, CS gas—tear gas—was deployed to clear the intersection," Dotson said.

"Peace was restored after a total of nine arrests—so nine individuals ranging from charges from impeding the flow of traffic to resisting arrest are now in our custody," Dotson added.

Around the time of the press conference, police say that they were responding to numerous reports of businesses burglaries as well as a car fire, which was set hours after the officers left the intersection.

One unverified video also showed a house consumed in flames, reportedly located near the scene of the police-involved shooting.

"So an area that's been plagued by violence, an area that's been plagued by gun violence, police officers were there today, doing the job that we all asked them to do to keep our community safe," Dotson said.

One reporter at the press conference asked whether the chief believed that the number of officers assigned to the area might have antagonized the group, who had assembled to peacefully protest.

"Well, I think that we have to look at the bigger pictured," Dotson replied. "Traffic is being stopped, they're not standing on the sidewalk, they're impeding traffic, they're marching through Kingshighway, which is a major thoroughfare... they're impacting people's lives."