A "prayer rally" began at Leimert Park as scheduled at 6 p.m., organized by Project Islamic H.O.P.E.
"Violence does nothing to help Trayvon and the Martin family get the justice they deserve and only distracts from the thousands of Americans who have signed petitions urging that the Justice Department pursue federal charges," Rep. Karen Bass, D-Los Angeles, said. "Our focus should continue to be on peaceful mobilization and active participation toward solutions. That's the best way to support the family during this very difficult time."
Mayor Eric Garcetti cut short a trip to the East Coast to return to Los Angeles Monday "out of an abundance of caution," according to a spokesman for the mayor.
By 8 p.m., several groups of protesters on foot were marching on Crenshaw Boulevard in the Crenshaw District. Some people in the crowd partially tore down a fence along the route. Some people clambered onto cars on the street.
By 9 p.m. the Los Angeles Police Department had declared a citywide tactical alert.
By 10 p.m. the LAPD declared an unlawful assembly in the Crenshaw area protest. Several people were arrested.
The LAPD said a local television photographer was hit in the back by suspect and a reporter was hit by the camera as a result. LAPD and LAFD personnel responded to the incident on Crenshaw.
In a news conference in Leimert Park at 11 p.m., Mayor Eric Garcetti, LAPD Chief Charlie Beck and L.A. County Supervisor Mark Ridley-Thomas spoke to the public and advocated for a calmer response to the events in Florida.
Sunday night, the LAPD had declared a citywide tactical alert as a result of protests the first day after Saturday's verdict. Demonstrators stormed The W Hotel before making their way to the CNN building late Sunday night in Hollywood. The W Hotel sustained minor damage. At least five people were arrested. The majority of the arrests were for failure to disperse, but clashes between demonstrators and police were minimal.
Earlier that evening, about 400 protesters brought traffic to a halt as they marched onto the eastbound 10 Freeway.
California Highway Patrol Officer Jennifer Cassidy says Interstate 10 by the Crenshaw Boulevard exit was closed for about 30 minutes due to the protestors. Some carried a large poster with a photo of Trayvon Martin, others rode bicycles as traffic came to a standstill.
By around 1 a.m. Monday, tactical alert had been canceled, with only the south and west bureaus remaining on modified tactical alert.
For the most part, demonstrators were non-violent but appeared to get more aggressive as the day went on. Police fired bean bag rounds at some protesters throwing rocks and bottles.
L.A. Mayor Eric Garcetti posted a message to the city on Twitter Sunday night.
"'Nonviolence is a powerful& just weapon. It is a sword that heals-MLK.' Exercise 1st Amendment and practice peace in City of Angels tonight."
Jurors reached the "not guilty" verdict Saturday, sparking a nationwide response from the NAACP, celebrities and citizens.
The NAACP called on the Department of Justice to prosecute Zimmerman in the February 2012 shooting of Martin in Sanford, Florida.
"We are outraged and heartbroken over today's verdict," NAACP President Benjamin Jealous said in a statement.
"We will pursue civil rights charges with the Department of Justice, we will continue to fight for the removal of Stand Your Ground laws in every state, and we will not rest until racial profiling in all its forms is outlawed," Jealous said.
Locally, Pastor J. Edgar Boyd of the First African Methodist Episcopal Church of Los Angeles shared his thoughts.
"My disappointment has come from the sense that I don't see enough advancement in the justice system in America today," said Boyd.
The DOJ previously launched a civil rights investigation into the case. A spokeswoman said the department would continue to "evaluate the evidence generated during the federal investigation, as well as the evidence and testimony from the state trial."
ABC News and the Associated Press contributed to this report.
