The effigies had names of lynching victims and the dates of their death. At least one effigy had "I Can't Breathe" printed on the front. Hamaoui said it's unclear who hanged the effigies.
"We are unsure of the intent," Hamaoui said.
Two of the effigies were removed by police and a student took down the third.
Organizers of the Berkeley protest were mystified as well.
"We just hope it's someone who wanted to bring attention to the issue," said Spencer Pritchard, 21, a UC Berkeley student and an organizer of the demonstration. Pritchard said about 200 protesters demonstrated in Berkeley with the goal to "disrupt business as usual to show that black lives matter."
Pritchard said many of the Berkeley protests plan on attending a demonstration against police brutality starting in Oakland at 2 p.m. PST. A similar demonstration is scheduled at the same time in San Francisco and elsewhere in the country.