A person has been fatally shot by a police officer in the St. Louis suburb of Berkeley, about two miles from Ferguson. The shooting took place shortly after 11 p.m. Tuesday.

Police have not identified the person killed. A woman named Toni Martin told the St. Louis Post-Dispatch he was her son, 18-year-old Antonio Martin.

St. Louis County police say the officer was conducting a routing business check and saw two people standing outside a gas station. He got out of his vehicle and approached them when one pulled out a handgun. That’s when, police say, the officer fatally shot the teen. The other person fled.

Berkeley Police have asked St. Louis County police to take over the investigation.

Protesters arrived after the shooting, many of them staying overnight.