About 80 protesters gathered in front of the CNN building in Hollywood on Sunset Boulevard shortly after midnight Monday, chanting "No Justice, No Peace," as police declared an unlawful assembly.
A police helicopter shone a light on demonstrators as more than 100 Los Angeles police officers in riot gear converged on the crowd and began making arrests and telling people to disperse. Some officers fired less-than-lethal rounds at the crowd.
The protesters had marched down to the CNN building from Hollywood Boulevard and Highland Avenue, with some carrying signs that said "We Are All Travyon Martin."Throughout the evening, police struggled to get a handle on pockets of protesters blocking traffic in the wake of the verdict in the George Zimmerman murder trial in Florida. The neighborhood watch volunteer was acquitted Saturday of fatally shooting the unarmed black teenager during a confrontation in February 2012.
Earlier, the LAPD called a citywide tactical alert after demonstrators blocked traffic on the eastbound 10 Freeway. The freeway was shut down from 6:30 p.m. to about 6:45 p.m.
Police emphasized that most of the protesters were peaceful. But there have been several splinter groups from the main protest that have been more aggressive, officials said.
LAPD Cmdr. Andy Smith said some demonstrators threw rocks and D-cell batteries at police near the corner of Washington Boulevard and 10th Avenue. Police responded by firing bean bags at demonstrators and arresting at least four people.
[Updated: 1:10 a.m., Monday: Los Angeles police arrested at least seven protesters throughout the day.]
Demonstrators also amassed in San Francisco, Oakland and New York City's Times Square on Sunday night.