New York's top prosecutor on Monday sought the power to probe all police killings of unarmed civilians in his state, following sometimes violent U.S. protests over two grand juries' moves to clear officers in the deaths of unarmed black men.

The morning after angry crowds hurled objects at police who responded with tear gas during protests in Northern California, New York Attorney General Eric Schneiderman said action is needed to address a "crisis of confidence" in the criminal justice system.

Cities across the United States have seen large protests in recent nights following a grand jury's decision not to charge an officer in the July killing of Eric Garner. An unarmed black father of six, Garner died after police put him in a banned chokehold.