Protesters hold a rally in support of former NYPD officer Peter Liang in the Brooklyn borough of New York February 20, 2016. [Xie Yun'an for chinadaily.com.cn]

Sean Yao, of United for Better Community (UBC), a Bay Area community outreach group, reminded the crowd that it is time for everybody to involve in America's political process, especially in the election year. "If you want change," Yao said, "you need to vote."

The city on the US west coast has seen tensions between its African American community and the police force since Dec. 2, 2015, when Mario Woods, a 26-year-old male, was confronted by officers after slashing a stranger. He reportedly refused to drop the knife, and was then shot by as many as 15 rounds fired by five officers.

Protestors against Liang's conviction believed this was the latest case of making the ethnic minority American a scapegoat to pay for the police brutality that has troubled the American society for a long time.