That was part of the “Days of Rage” in October 1969 (when 0bama was only 8 years old), a year or two before they went on their national bombing rampage and were suddenly wanted by the FBI.
http://www.onthisdeity.com/8th-october-1969-%C2%A0the-weathermens-days-of-rage/
“After less than half-an-hour, the three hundred or so demonstrators were outnumbered by 1,000 cops; in the resulting melee, six Weathermen were shot and 68 arrested.”