“A black security guard was shot dead by a police officer as he held down a suspect in a shooting at the bar where he worked. Jemel Roberson, 26, was working early Sunday … when a patron who … had been kicked out returned with a gun … and opened fire …. Several people were shot. Roberson … held him down and waited for police …. A responding officer … immediately shot Roberson … [even though] people on the scene tried to warn police that Roberson was a security guard.”