(Adds details from late-night protests)
By Nick Carey and Carey Gillam
FERGUSON, Mo., Aug 13 (Reuters) - Police in Ferguson, Missouri, fired several rounds of tear gas to disperse protesters late on Wednesday, on the fourth night of demonstrations over the fatal shooting last weekend of an unarmed black teenager by a police officer.
Clouds of smoke lingered above an area hit with police tear gas police as the crowd of some 350 protesters scattered off into side streets and into cars. Someone from the crowd appeared to throw an object at police.
Two journalists, Wesley Lowery of the Washington Post and Ryan J. Reilly of Huffington Post, were arrested on Wednesday, and then released, while working in the area.
Michael Brown, 18, was shot to death in the mostly black suburb of Ferguson, Missouri on Saturday after what police said was a struggle with a gun in a police car.
A witness in the case told local media that Brown had raised his arms to police to show that he was unarmed before being killed.
Protesters have gathered in the St. Louis suburb every night since in tense standoffs with heavily armed police.
"I've had enough of being pushed around because of the color of my skin, I'm sick of this police brutality and I'm angry cause of what they done to Michael Brown," said one protester, 18, who would identify himself only by his first name, Terrell.
"I'm going to keep coming back here night after night until we get justice," he said.
Police have been slow to release information about the shooting, except to say that it followed a struggle between the unnamed officer and Brown.
DETAILS IN DISPUTE
Details about the incident are in dispute. A witness who was walking with Brown at the time has said in media interviews that Brown put his hands in the air and was not struggling with the officer. He said the officer fired multiple times into Brown's head and chest.
The witness, Dorian Johnson, was expected to meet on Wednesday with prosecutors and investigators, local media reported. His lawyer, Freeman Bosley, a former St. Louis mayor, did not immediately answer requests for comment.
Police have declined to release the name of the officer involved in the incident, citing concerns for his safety, a decision that has been criticized by demonstrators who have asked for more transparency. The officer has been placed on administrative leave.
Police Chief Thomas Jackson told a news conference earlier on Wednesday that his priority was improving race relations in Ferguson, which has seen a stark demographic shift in recent decades, going from mostly white to mostly black. About two-thirds of the town's 21,000-strong population are black. On a police force of 53, three officers are black.
"This is an opportunity to fix what's wrong," he said.
The local Ferguson-Florissant school district meanwhile postponed its first day of classes until Monday, cancelling classes for this Thursday and Friday.
TRYING TO MAKE SENSE OF IT
Ferguson residents were still trying to make sense out of what happened on Wednesday.
"I cannot condone violence, but I definitely understand where the anger of young black men comes from at times like this. I don't think until you've experienced that kind of treatment that you can understand it," said Mike McCoy, 41, who runs an African-American youth program.
McCoy, who said he has been a victim of racial profiling by local police, was visiting a memorial of candles, teddy bears and messages near where Brown was killed.
National figures from President Barack Obama to civil rights activist Rev. Al Sharpton have called for a peaceful response to the shooting.
About 40 protesters have been arrested since Saturday.
After Tuesday night's protests were broken up by tear gas, a St. Louis County Police officer shot and critically wounded a 19-year-old male who allegedly pointed a gun at the officer. The man, who was identified on Wednesday evening as Esran Britton, had been involved with the earlier protests, police said.
"I have been in fear since Saturday night that something like this would happen," Jon Belmar, the St Louis County police chief, said at an evening news conference. "It's remarkable that we haven't had more problems but I am hopeful the unrest will come to an end soon."
Meanwhile, police in California were investigating a separate incident of an officer fatally shooting an unarmed 25-year-old black man in Los Angeles.
On social media, groups claiming to be associated with the Anonymous hacker activist group called for nationwide protests and threatened to reveal personal information about Ferguson police officers.
The Ferguson police said there have been attempts to hack their website and that it was temporarily disrupted.
Ferguson Police spokesman Tim Zoll said the cyber-threats prompted the decision not to release the officer's name. (Additional reporting by Brendan O'Brien in Milwaukee; Writing by Fiona Ortiz; Editing by Edith Honan, Eric Walsh and Jeremy Laurence)