On Wednesday, St. Louis police shot and killed a black teenager whom they say pointed a gun at them, drawing angry protesters and sparking racial tensions.

Violence erupted approximately a quarter of a mile from where there had been a demonstration for the anniversary of last year’s killing of unarmed black teenager Michael Brown. The shooting came 10 days after protestors descended on St. Louis to mark the anniversary of the Aug. 9.

Protests from Wednesday’s shooting led to police making nine arrests and using tear gas to clear a street where about 150 people gathered.

St. Louis Police Chief Sam Dotson said Wednesday’s shooting took place as officers were carrying out a search warrant and two young black men ran out the back door of the targeted house. Officers ordered the pair to stop in the alley behind the house. Police say 18-year-old Mansur Ball-Bey was armed with a firearm with an extended magazine, and the other suspect was armed with two guns and was in possession of crack cocaine. Dotson said Ball-Bey pointed a gun at officers who then fired about four times and killing him.

Demonstrations began as a response to the police shooting as a crowd gathered in the street near the site of the shooting. Dotson said officers made repeated requests to the group to clear the intersection and move to the sidewalk. When the group did not comply, Dotson said officers arrested some, and that prompted others to move out of the street. Dotson said when officers approached the group again, protesters began throwing glass bottles and bricks at the officers, who had to use shields to protect themselves. Police begun launching tear gas and rubber bullets against protesters.

St. Louis police said the officers involved in the shooting were both white, ages 33 and 29, with about six and seven years on the force. They are currently on administrative leave.