WATCH LIVE: St. Louis activists demonstrate after police shoot and kill 18-year-old

Demonstrators marched in St. Louis early Thursday morning after a local police officer reportedly shot and killed an 18-year-old man.

According to the St. Louis Post-Dispatch, protesters began gathering in a neighborhood on the city's south side after the unidentified officer shot Vonderrick Myers Jr.

The officer was allegedly working a second job as a private security guard when he stopped Myers and three other pedestrians around 7:30 local time. Witnesses described the encounter as a "pedestrian check," comparable to the "stop and frisk" policy employed by officers in New York City.

A police spokesperson said Myers ran away from the officer, before struggling with him and allegedly drawing a gun toward him, a claim several witnesses have disputed.

"He was unarmed," Myers' cousin, Teyonna Myers, told the Post-Dispatch. "He had a sandwich in his hand, and they thought it was a gun. It's like Michael Brown all over again."

The fatal shooting of Brown, who was also 18 years old, by Officer Darren Wilson in nearby Ferguson, Missouri on Aug. 9 sparked protests both locally and around the country. A group of demonstrators interrupted a performance by the St. Louis Symphony to sing a song in Brown's memory and display a banner bearing his face.

Watch a livestream of the protest, as posted on Livestream by "Rebelutionary Z," below.