Oh look, there’s Opie. and the guy on the far right looks like one of the guys arrested the first night.
Retaining wall bricks apparently from landscaped areas at intersections. Probably accummulated all that while the marchers were well down the street.
BUT - I wonder if forward observers could have noticed that activity, and neutralized or isolated it before the marchers got there. The marchers were loud but peaceful with a banner carrier at the front and probably would have been easy to stop if someone had communicated with them that trouble was brewing at the line. Another fail on crowd control.
I’ll have to go back and see if I can pull of KGAR tapes where he commented that there was some alleged tension between organizers and police.