African Americans throughout US history have been activists for reform and still are not heard. To this day, marches, rallies, and protests are held by minorities to get their voices heard. This is especially present in modern day police reform.
People of color are often scared or worried about calling the police as they think that they will not take their situations seriously. While they believe white people's issues are taken more seriously.
This is a trivial statement because it's necessarily true via the definition of "oppressed." It can be translated to "Those who are oppressed are oppressed." I think you mean to ask about the poor, or minorities maybe?
The top three races per million people killed by police in 2015 and in 2016 are minority races in the United States. These are African American, Latino, and Native American.