protesters threw bricks, rocks, other projectiles with paint at police. officers tried to clear out those crowds and others shattered windows of businesses along the street. >> we are learning nine people were arrested and today's concert in st. louis has been cancelled amid the security concerns. protesters are frustrated with a jum's decision to acquit former st. louis police officer jason stockily in the 2011 shooting death of anthony lamar smith. cnn's ryan young was in st. louis as the violence started. >> reporter: we are on delmar boulevard. you can see the heavy machinery behind me that the police brought in here. there is a bearcat. the officers in their riot gear. about 50% of the businesses had coming down delmar boulevard look like they suffered some sort of damage. the organizers told peaceful marchers to go home but a half hour after that, we saw another group that decided to stay here. that started to build and there was a confrontation between