Civil rights leaders are condemning the ambush killings of two New York police officers and expressing fear that the backlash over the bloodshed could derail the protest movement that has emerged around the deaths of Michael Brown and Eric Garner.

Shortly after the ambush, police union officials and politicians accused protesters of fanning anti-police fervor and contributing to the atmosphere that got the officers killed.

Civil rights leaders such as the Rev. Al Sharpton said the criticism is misguided. NAACP President Cornell Williams Brooks said it is "simply not fair" to link "the criminal insanity of a lone gunman" to the recent protests.