Protests and tear gas in Ferguson, Mo., Monday night

Police in riot gear fired tear gas into a crowd of protesters in a St. Louis suburb where an unarmed black teenager had been fatally shot by police over the weekend, as tension rose even amid calls for collective calm.

Between two nights of unrest, a community forum hosted by the local NAACP chapter Monday night drew hundreds to a sweltering church in Ferguson, the nearly 70 percent black St. Louis County suburb where an unarmed 18-year-old, Michael Brown, was shot multiple times by a police officer.

Ferguson Police Chief Tom Jackson said a large crowd that gathered throughout Monday at the site of a burned-out convenience store turned rowdy at nightfall, throwing rocks at police. Officers used tear gas and shot "beanbag rounds" meant to stun them, he said.

St. Louis County police spokesman Brian Schellman said there were at least five arrests and no reports of looting. Nearly three dozen people were arrested following a candlelight vigil Sunday night when crowds burned stores, vandalized vehicles, assaulted reporters and taunted officers.

"People are tired. They have reached the end of their rope," said Ruth Latchison Nichols after the NAACP forum, where many more were left waiting outside once the pews reached capacity. "Enough is enough. This is a state of emergency."

National NAACP President Cornell William Brooks implored residents to "turn your anger into action" while condemning the violent response to Brown's death.

"To sneak around under the cover of darkness, to steal, to loot, to burn down your neighborhood — this does not require courage," he said. "Courage is when you strive for justice."

"Martin Luther King did not live and die so that we may steal and lie in the middle of the night," he added.

The FBI has opened an investigation into Brown's death, looking into possible civil rights violations. Witnesses have said that Brown had his hands raised when the unidentified officer approached with his weapon drawn and fired repeatedly.

Brown's parents have been among those calling for calm. His family, who had planned to drop him off at a technical college Monday to begin his studies, have asked people to share any information and videos they might have related to the shooting.

Authorities have been vague about what led the officer to open fire, saying only that the shooting — which is being investigated by the St. Louis County police at the smaller city's request — was preceded by a scuffle of some kind with a man in which the officer's weapon discharged once inside a patrol car.

Investigators have refused to publicly disclose the race of the officer, who is now on administrative leave. But Phillip Walker said he was on the porch of an apartment complex overlooking the scene when he heard a shot and saw a white officer with Brown on the street.

Brown "was giving up in the sense of raising his arms and being subdued," Walker told The Associated Press. The officer "had his gun raised and started shooting the individual in the chest multiple times." The officer then "stood over him and shot him" after the victim fell wounded.

Dorian Johnson offered a similar account, telling KMOV-TV that he and Brown were walking home from a convenience store when a police officer told them to get out of the street and onto the sidewalk. Johnson said they kept walking, which caused the officer to confront them from his car and again after getting out of the vehicle.

Johnson said the first time the officer fired, he and Brown got scared and ran away.

"He shot again, and once my friend felt that shot, he turned around and put his hands in the air, and he started to get down," Johnson said. "But the officer still approached with his weapon drawn and fired several more shots."

"We wasn't causing harm to nobody," Johnson said. "We had no weapons on us at all."

Walker said that he did not see a scuffle or the circumstances that preceded the first gunshot.

Jackson, the Ferguson police chief, said there's no video footage of the shooting from the apartment complex or from any police dashboard cameras or body-worn cameras that the department recently bought but has not yet put to use.

Some civil rights leaders have drawn comparisons between Brown's death and that of 17-year-old Trayvon Martin, who was fatally shot by a Florida neighborhood watch organizer who was later acquitted of murder charges.

"Instead of celebrating his future, they are having to plan his funeral," said Benjamin Crump, a family attorney who also represented Martin's relatives after he was slain in 2012 in Florida.

I don't want to sugarcoat it," Crump added. Brown "was executed in broad daylight."

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Associated Press reporters Jim Salter, Jeff Roberson, Jim Suhr and David Lieb in Ferguson and Eric Tucker in Washington and AP researcher Rhonda Shafner in New York contributed to this report.

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