The group that organized a demonstration in Dallas that ended when a gunman ambushed police is planning a silent march to protest police treatment of blacks.

Next Generation Action Network founder Dominique Alexander said Tuesday that the march on Friday night is intended to "keep the pressure on" Dallas police to respond to protesters' demands for changes.

The group organized a July 7 protest in downtown Dallas after recent police shootings of black men in Minnesota and Louisiana. That demonstration was peaceful until Army veteran Micah Johnson opened fire, killing five officers and wounding nine others and two civilians. Police killed Johnson.

Friday's march was originally scheduled for last week. Dallas Police Association vice president Mike Mata said Alexander postponed it when officers told him "it was just too soon."