St Louis unrest after police killing of teenager
US police have clashed with protesters in Missouri after an officer shot dead a black teenager close to where another black youth, Michael Brown, was killed in August sparking national protests.
A crowd of about 100 gathered at the scene in St Louis early on Wednesday after scuffles the night before.
Police said the man who was shot, Antonio Martin, 18, had pointed a gun at the police officer.
For weeks there have been widespread protests over alleged police brutality.
Berkeley is about two miles (3km) from the St Louis suburb of Ferguson, where 18-year-old Michael Brown was shot dead by a white officer.
'Bad choices made'
St Louis County police chief Jon Belmar said a police officer was responding to a call about a theft when he saw Mr Martin and another man at a petrol station in North Hanley Road and approached them.
He said that Mr Martin pointed a handgun at the officer, and the officer responded by firing three shots. One of the shots hit Mr Martin, he said.
The officer "responded with what he thought was commensurate force at the time", Col Belmar said, adding that "most of us would feel in imminent danger of losing our lives at that point".
Col Belmar described the incident as "a tragedy for everybody", and said a prosecutor had been assigned to investigate the case.
"Our hearts certainly go out to the family, but bad choices were made," he added.
"This individual [Mr Martin] could have complied with the officer; he could have run away; he could have dropped the gun. Things did not have to end with him approaching an officer with a 9mm pistol in his hand."
Berkeley Mayor Theodore Hoskins said that both the city and St Louis County would hold independent investigations.
The incident could not be compared with the shooting of Michael Brown in Ferguson, Mr Hoskins said, adding: "The video shows that the deceased pointed a gun... at the officer."
Between 200 and 300 people gathered at the scene after the incident, Col Belmar said, adding that bricks were thrown at police officers, and three explosive devices set off.
Four people had been arrested for assaulting police officers, he said.
Police are releasing video footage of the run-up to the shooting, and an image of the second man, who fled the scene.
The handgun said to belong to Mr Martin has been recovered by police.
Some protesters remained near the petrol station on Wednesday.
One, Orlando Brown, told AP news agency: "I understand police officers have a job... but do you have to treat every situation with lethal force?
"It's not a racial issue, or black or white. It's wrong or right."
Recent police killings in the US
- December 2014: Akai Gurley, 28, was shot by a rookie police officer while walking into his apartment building in New York. Mr Gurley was not armed
- November 2014: Tamir Rice, 12, was shot in Cleveland, Ohio, after a 911 caller told police he was pointing a gun at people in a park. The gun was later found to be a toy
- July 2014: Eric Garner, 43, died after being held down by a New York police officer in an apparent "chokehold". He had been stopped on suspicion of selling untaxed cigarettes
- April 2014: Dontre Hamilton, 31, was shot 14 times by a white police officer in Milwaukee, Wisconsin, after police received a complaint about him sleeping in the park. The officer said he resisted arrest
Relations between police and local communities have become increasingly taut in recent months.
In August, Michael Brown, who was unarmed, was killed by a white police officer who said he opened fire after a struggle in a patrol car in Canfield Drive, Ferguson.
His death sparked protests, sometimes violent, and further unrest followed a grand jury's decision not to charge the officer.
There were further demonstrations after the death of Eric Garner, 43, a black man who died while being held down by a white police officer in July in New York. Again, a grand jury decided against charging the officer.
On Saturday, New York police officers Wenjian Liu and Rafael Ramos were shot dead by gunman Ismaaiyl Brinsley, who then killed himself.
Brinsley, who had a history of violence and mental instability, had posted anti-police messages online, referring to the deaths of Michael Brown and Eric Garner, before the shooting.