Protests in Ferguson dwindle, mass arrests at California rallies (Reuters) - Tensions eased in the St Louis suburb of Ferguson on Thursday after two nights of violence and looting sparked by racially charged anger over a grand jury's decision to clear a white police officer in the shooting death of an unarmed black teenager. Protests also dwindled elsewhere in the United States as the Thanksgiving Day holiday and wintry weather kept many indoors. But in California, more than 250 people were arrested in rallies over the past two days that shut highways in major cites. Ferguson became the focal point of a national debate on race relations after officer Darren Wilson shot dead Michael Brown on Aug. 9. The U.S. Justice Department is probing possible civil rights abuses, and President Barack Obama has called for reflection on the difficulties minorities face in the country. Police said two people were arrested in overnight protests in Ferguson. The grand jury's decision on Monday not to charge Wilson sparked angry protests, and more than 100 people were taken into custody on Monday and Tuesday nights as buildings were torched and stores looted, with police in riot gear using tear gas to disperse crowds. Protests will continue. This has ignited everyone's desire for change," said Pam Ned Davis, one of a handful of people who turned out for a Wednesday night protests in Ferguson that police said were without major incident. Ferguson is a predominantly black city where almost all of the political leaders and police are white. In Los Angeles, a city rocked by racial violence in 1992 after the acquittal of white police officers in the beating of black motorist Rodney King, several hundred protesters blocked traffic as they marched through downtown, yelling, "No justice, no peace" on Wednesday. Police said more than 50 people were arrested for ignoring orders to disperse. About 500 people have been arrested nationwide in Ferguson-related protests. At least 200 people ran through streets in Oakland, the gritty neighbor of San Francisco, spraying walls, billboards and bus stops with graffiti and smashing storefront windows, before they were confronted by police near City Hall. In San Diego, about 300 protesters with a heavy police escort marched peacefully through the City Heights district chanting, "Ferguson, we've got your back." Overseas, protesters held up banners reading "Solidarity with Ferguson" and "Black Lives Matter" outside the U.S. Embassy in London. In Ferguson, businesses were boarded-up or burned along a mile-long stretch of West Florissant Avenue, which bore the brunt of Monday's lawlessness, and downtown streets between the police department and City Hall. Missouri Governor Jay Nixon, who declared a state of emergency before the grand jury decision, has deployed about 2,200 National Guard troops to the Ferguson area to quell violence. Wilson, who was placed on administrative leave, has said he acted in self-defense, out of fear for his life, when he shot Brown. Brown's family said he acted with malice and should stand trial. Additional reporting by Alex Dobuzinskis and Daina Beth Solomon in Los Angeles, Emmett Berg in Oakland, Zachary Goelman in San Diego, Carey Gillam in Kansas City, Writing by Steve Gorman and Jon Herskovitz; Editing by Andrew Heavens and Cynthia Osterman