St. Louis police fatally shot a black teenager on Wednesday who they say pointed a gun at them, and later faced angry crowds, reigniting racial tensions first sparked by the killing of an unarmed black teen in another Missouri town a year ago. St. Louis Police Chief Sam Dotson said the shooting took place when young black men ran out the back door of a house where officers were carrying out a search warrant, Reuters reported. Officers ordered the pair to stop in an alley behind the house. One suspect pointed a gun at officers who then fired four times, killing him, Dotson said. "Detectives were looking for guns, looking for violent felons, looking for people that have been committing crimes in the neighborhood," he said. Police identified the slain suspect as Mansur Ball-Bey, 18. The second youth fled. Crowds gathered at a nearby intersection shortly after the shooting and then again in the evening. Dotson said at a late Wednesday press conference some protesters threw bricks and glass bottles at officers, who used shields to protect themselves and then tear gas to disperse the crowd. A car was set on fire and some local businesses had reported robbery attempts, he said. Nine people were arrested on charges of impeding traffic and resisting arrest, police said. St. Louis Alderman Antonio French posted on Twitter that a vacant house was burning. Dotson told reporters Ball-Bey's gun was one of three stolen firearms recovered from the scene and said officers recovered crack cocaine. St. Louis police said the officers involved in the shooting were white, aged 33 and 29, each with about seven years on the force. They are on administrative leave. A 93-year-old member of the Tuskegee Airmen, a black aviation unit from World War Two, was robbed and carjacked in the neighborhood on Sunday. A woman was also killed in the area this week. The shooting came 10 days after St. Louis was flooded with protesters marking the anniversary of the killing of unarmed black teenager Michael Brown by a white police officer on Aug. 9 last year in Ferguson, not far from St Louis.. Brown's death helped spark a nationwide movement against what protesters say is police violence against minorities. Wednesday's shooting also came as activists were in the area to mark the anniversary of the police shooting of another black man in St. Louis, Kajieme Powell. Police say officers shot Powell when he approached them with a knife.