Police and civic leaders braced for unrest while appealing for calm on Tuesday after nearly two dozen protesters in Los Angeles and Oakland were arrested during a second night of civil disturbances sparked by the Trayvon Martin trial in Florida.
Police in Los Angeles said the lawlessness was committed by about 150 people who broke off from an otherwise peaceful prayer vigil held in memory of Martin, the unarmed black teenager who was shot to death last year by a neighborhood watch volunteer in Florida.
The white-Hispanic man who shot Martin, George Zimmerman, was found not guilty of murder and manslaughter charges on Saturday after a three-week trial in the racially charged case, a verdict that has stirred demonstrations across the country.
In the predominantly black Crenshaw District of Los Angeles, vandals set rubbish fires, smashed windows and assaulted members of a television news crew during several hours of unrest on Monday night.
Fourteen people were arrested, most of them for failing to heed orders to disperse, police said. One person was arrested during similar outbursts on Sunday night.
In Oakland, across the bay from San Francisco, about 250 protesters swarmed downtown streets on Monday night, vandalizing cars and businesses and scrawling graffiti. Nine people were arrested.
No serious injuries were reported in either city. But officials called for demonstrators to keep rallies peaceful.
"The trial that we saw in Florida has ignited passions, but we have to make sure that it will not ignite this city," Mayor Eric Garcetti told a late-night news conference. "The Martin family was very clear that those who sympathize with their plight, the best way to honor their son and their loved one is in a nonviolent manner."
Police Chief Charlie Beck, appearing with the mayor, warned that his officers would take "a much stricter posture in the way that we deal with people taking the streets" around Crenshaw and urged parents to keep children away from further protests there.
A statement signed by Oakland Mayor Jean Quan and other city officials acknowledged "the death of Trayvon Martin as a tragic event felt throughout the community."
"We understand the verdict announcement is an emotional one. We are committed to supporting peaceful assembly and freedom of speech," it added.
Hoping to head off a third night of disturbances in Los Angeles, civic leaders planned to deploy a team of "peace monitors" on street corners in the area, said community activist Earl Ofari Hutchinson.
He said opportunism from trouble-makers seeking to exploit the situation was a factor on Tuesday, but the Zimmerman acquittal was also the latest flashpoint for pent-up anger, frustration and a sense of disconnect within the community.
"Many are angry over the (Zimmerman verdict); they think it was unjust," he said.
In San Francisco, a group that organized protests of the Zimmerman acquittal in various cities was planning a demonstration on Tuesday to mark the second anniversary of another fatal shooting with racial overtones, the killing of a black bus passenger by police after he failed to pay his fare.
The group, Act Now to Stop War and End Racism, threatened to shut down San Francisco's municipal bus service on Tuesday afternoon in an act of civil disobedience.