LA Trayvon Martin Protests Turn Ugly

Los Angeles officials have appealed for calm after protests turn violent over the acquittal of a neighbourhood watchman who killed a black teenager.

Thirteen people were arrested amid vandalism and assaults in the California city's Crenshaw district.

The city's police chief said his officers would adopt a tougher approach to any further disturbances.

George Zimmerman, 29, was acquitted on Saturday of 17-year-old Trayvon Martin's death in Florida last year.

Federal officials are now investigating potential civil rights charges against Mr Zimmerman.

Street assaults

Los Angeles police said about 150 people splintered off from a peaceful vigil on Monday, some of them jumping on cars and breaking windows at fast-food outlets.

Several protesters vandalised a Walmart in the neighbourhood. Broadcast news footage from helicopters showed some of the troublemakers kicking and punching people on the street.

Police, who brought 300 officers to the scene, declared an unlawful assembly about three hours later, and most people left soon after.

In a late-night news conference, Los Angeles mayor Eric Garcetti praised the "overwhelming majority" who protested peacefully.

"We are a better city than what we have seen tonight in the hands of a few people," the mayor said, characterising those who took part in the vandalisms and assaults as opportunists.

Meanwhile, in the city of Oakland, California, protesters briefly shut down a highway during rush hour.

Police made several arrests amid disturbances in the centre of that city late on Monday.

Rocks and bottles were thrown at Oakland police officers, the San Francisco Chronicle reported.

It was the third night of protests in the state of California, but cities across the US have seen demonstrations and vigils.

The largest protest against Mr Zimmerman's acquittal was in New York on Sunday, where thousands converged on Times Square.