Washington: In the latest incident to fuel tension between US police and the black community, a teenager was shot dead by a white officer in a suburb of St Louis, ground zero of a new protest movement.
St Louis county police chief Jon Belmar said an 18-year-old suspect levelled a gun at an officer responding to a theft complaint at a gas station, leaving him with no alternative but to shoot.
But the death in Berkeley -- a St Louis suburb immediately bordering Ferguson, in recent months the scene of a more controversial police shooting and subsequent riots -- triggered immediate protests.
Belmar said two men approached the officer's car as it approached the gas station. One suspect pointed his nine-millimeter pistol at the officer, who drew his own weapon and fired three shots.
"The individual produced a pistol with his arms straight out pointing at the officer across the hood of the police car at that point the policed officer produced his service weapon and fired," he said.
Police are hunting for the second man who fled the scene.
St Louis police released surveillance footage from the gas station, but said the officer -- a 34-year-old white man with six years experience on the force -- was not wearing his body camera.
The suspect was named in US media reports as 18-year-old Antonio Martin. Police did not confirm this, but said the suspect was known to police for assault and robbery charges.
A 300-strong crowd gathered after the shooting, with demonstrators lobbing bricks and three explosive devices, which officials said were likely fireworks. Police responded with pepper spray.
A small group was seen looting a shop close to the scene of the shooting. At least one officer was injured and is in hospital after the clashes.
Belmar said "bad choices" were made by the suspect, and defended the officer's decision to shoot.
"This individual could have complied with the officer, he could have ran away, he could have dropped the gun... It didn't have to end with him approaching the officer with an arm extended and a nine-millimeter pistol in his hand," he said.
"I would imagine that most of us would feel like we were in imminent danger of losing our lives at that point and I think the officer responded with what he thought was commensurate force."
Some reports, however, said some eyewitnesses disputed that account.
A woman who identified herself as the victim's mother, Toni Martin, said her son was running when her was shot and killed.