Three people were arrested in connection with protests in Los Angeles that followed Monday's announcement in Missouri that a grand jury had decided not to bring charges against a white police officer in the shooting death of an unarmed black teenager.

LAPD headquarters marked the site of the most sustained protest, which carried on well into Tuesday morning. The protest was largely peaceful, despite three arrests -- the details of which were not immediately available.

The crowd eventually dispersed at around 3:30 a.m., with another protest scheduled for Tuesday at 3 p.m. at Crenshaw Boulevard and Martin Luther King Jr. Boulevard.

It came after crowds of protesters had marched through parts of Los Angeles on Monday, blocking traffic and threatening to get on freeways, Monday night following the grand jury decision not to prosecute Ferguson, Missouri police officer Darren Wilson, who shot unarmed teenager Brown in August during a confrontation.

One protest reached the world famous Rodeo Drive in Beverly Hills, where demonstrators sat down in the middle of an intersection as police kept watch. The protesters gathered in silence for 4 and a half minutes, symbolizing the amount of time Brown wa on the street in Ferguson without medical attention.

A group of up to 70 protesters were blocked by LAPD and CHP officers from getting onto the 10 Freeway at La Brea Avenue. There were no arrests and all lanes remained open.

Police also shut down ramps to the 110 Freeway in Exposition Park to dissuade demonstrators from entering the freeway. Shortly after 11:30 p.m., a large group of protesters caused the 110 to close near the Los Angeles Convention Center by blocking traffic and refused to follow a request from CHP to disperse. However the road had reopened by 12:29 a.m. in both directions. Police used nonlethal projectiles to disperse crowds when crowds refused to leave the downtown area.

The USC campus was placed on lockdown as demonstrators marched past. A splinter group of about 50 people began marching down Crenshaw Boulevard as police helicopters monitored them.

The protests remained mostly small and peaceful.

In a statement issued from Asia where he is on a trade mission, Mayor Eric Garcetti said, "Michael Brown's death has ignited deep passions across the nation, and Los Angeles is no exception.

"Tonight's decision is one that will be heatedly debated -- but we should do so through dialogue and peaceful action. City departments are mobilized to assist in the exercise of peaceful protest."

The demonstrations came as Southern California community leaders and elected officials continued to plead for calm.

However, at a public rally being held in in Leimert Park, where passions were running high.

"He got away with murder. He murdered Michael Brown. And right now he's going to get away with it," Najee Ali of Operation Islamic Hope said.

"We're getting ready to tell America in a very bold nonviolent way that we are tired of the murder of our boys on the streets of America," Pastor William Smart said.

"We're getting sick and tired of it, and we're going to continue to demand justice at a federal level," Rev. K.W. Tulloss of the National Action Center said.

The LAPD was placed on a citywide tactical alert in anticipation of the potential unrest. LAPD’s Department Operations Center was activated in anticipation of the Ferguson decision.

This is a significant, rare move by law enforcement only done when trouble is anticipated, police said.

The DOC acts as central hub to manage citywide response and call in extra resources. Incident commanders and watch commanders will be report to the DOC.

Businesses, including stores and bars, were notified of the impending announcement should they wish to close for the day.

Police Chief Charlie Beck said last week the department was reaching out to the community to encourage peaceful protests in response to the Ferguson decision. He said officials were also keeping in touch with Missouri authorities so the LAPD can be prepared in advance of the announcement.

"We've done significant outreach in all our communities," Beck said. "All our commands are ready to increase deployment if that is needed. We believe the outreach we have done will ensure that people are not only able to protest if they so desire, but will protest in a lawful matter."

"This is an issue that we are all concerned with, but I believe the relationship with the Los Angeles Police Department and the communities that are most concerned is very strong," he said. "And we have made sure we have had discussions with leadership all over the city about what our position is and how we will support their lawful demonstration of either support or discontent with whatever the grand jury does."

Tena Ezzeddine and City News Service contributed to this report.