Authorities in a suburb of the US city of St Louis, where an unarmed black teen was shot and killed by a police officer, have used tear gas to try to disperse protesters after flaming projectiles were thrown from the crowd.

Police also used smoke bombs on Wednesday night, after directing people to go home. Helicopters circled overhead and smoke hung in the air.

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. Protester

St Louis County police spokesman, Brian Schellman, said he had no immediate information about the situation.

Michael Brown, 18, was shot dead in the mostly black suburb of Ferguson 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 [be]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.

Journalists arrested

Police have been slow to release information about the shooting, except to say that it followed a struggle between the unnamed officer and Brown.

Earlier on Wednesday, authorities urged people to confine their protests to daylight after three nights of tense confrontations, looting, tear gas and a second shooting nearby.



An Al Jazeera journalist was tear-gassed, and two other reporters covering the protests said they were arrested at a McDonald's restaurant.

Al Jazeera's Ash-Har Quraishi said the team had thought they had reached a safe area when they were tear-gassed.

"The Al Jazeera crew were in a place we believed to be safe," he said.

"Soon afterwards people started running towards us saying they were being fired on with rubber bullets. Rubber bullets were fired on us, and then a canister. We had to retreat into the neighbourhood."

Wesley Lowery of The Washington Post and Ryan Reilly of The Huffington Post say they were working in the fast-food restaurant when SWAT officers came in to quickly clear the area.

Both quickly tweeted about their arrests , detention and subsequent release without any charges.

Ferguson Police Chief Tom Jackson did not immediately return a cellphone message from the Associated Press news agency seeking comment.