Here's the New York Times account of how it happened:
For a few minutes, as the police awaited the final command, the demonstrators' loudspeaker worked, and one of their leaders ordered the protesters to sit down and hold hands before the police moved in.
They chanted, shouting "The police are with the people!" and "Truth! Truth! Truth!" but offered no resistance visible to journalists, who were ordered by the police to stand about 50 yards away.
The demonstrators were easily outmatched. The police carried away the first few protesters and loaded them onto trucks, and in a few minutes the remainder of the demonstrators, who appeared to be at least 300 strong, left in orderly columns and boarded waiting buses and trucks.
Some raised their fists in defiance as they boarded. The operation was over in less than 25 minutes.