Tense confrontations between police and protesters took place in St. Louis, following the fatal shooting of 18-year-old Vonderrit Myers Jr., by an off-duty police officer on Wednesday.

Demonstrators reportedly gathered on Grand Boulevard in the city Thursday and were watched from afar by police officers for most of the evening. However, according to a report from the New York Times, around 10 p.m. local time (11 p.m. EDT), officers in riot gear and armed with pepper spray began to move into the crowd. It was not immediately apparent what caused the police to advance.

New York Times reporter Alan Blinder subsequently tweeted that police had used pepper spray against a group of demonstrators. Other reports on social media appeared to support this account. 

Paul Hampel, a reporter for the St. Louis Post-Dispatch, tweeted that police had ordered protesters off the street and wrestled a demonstrator to the ground. He described the situation as “volatile... to say the least.”

Valerie Schremp Hahn, a journalist with the St. Louis Post-Dispatch, reportedly said that a protester who saw her tweeting about a man breaking up bricks grabbed her in a headlock and attempted to take her phone. Schremp Hahn reportedly screamed “Get away from me! Get away from me!" and ran toward the crowd. She added that protesters subsequently told her that they “kicked the guy out."

Matt Sczesny of KMOV tweeted a picture of a folding knife that he said had been thrown at a police officer.

Sam Dotson, chief of police for the St. Louis metropolitan police department, reportedly said that some officers used pepper spray on “some protesters as they became aggressive toward officers.” He also reportedly added that “protestors had a certain aggression we didn't see last night... More than you can count on one hand that are agitators.”

The narrative over the events surrounding Myers' fatal shooting is disputed

Police say that ballistic evidence shows that the teen shot at least three times at an off-duty police officer, who was working a second job for a private security company. Myers' relatives claim that he was unarmed, and that the officer mistook a sandwich for a gun.

Brian Millikan, the attorney representing the as-yet unnamed police officer involved in the shooting, told the St. Louis Post-Dispatch that his client is lucky to be alive because he hesitated too long before firing at an 18-year-old who pointed a gun at him.

"He's fortunate the guy missed him,” adding that he welcomed any outside investigation of the incident. "We welcome any fact finder...Who is looking at it through a factual lens, not a political lens," he said.

Millikan also said that claims that Myers was carrying a sandwich and not a gun were "ridiculous."

Missouri has seen a sharp spike in tensions between the black community and police following the shooting two months ago of black teenager Michael Brown by officer Darren Wilson in Ferguson. The U.S. Department of Justice is conducting a federal civil-rights investigation into the Ferguson police department. A state grand jury is also considering whether to bring charges over Brown's killing.