How do the riot police quell the disturbance at the hospital for the dying?
The police end the riot by pumping drugs into the air, sedating everyone past the point of resisting or even caring. This disturbance is created after John has watched his mother die. He has suffered from the matter-of-fact approach the children have taken, & he is overcome with emotion. Yet he has no outlet for his pain. He continually cites lines from The Tempest, hoping to reach others, but there is no community here: only surface level, shallow interactions.
When John steps off the elevator & finds the Delta shift receiving their soma rations, he simply can't take it. He throws soma out the window, encouraging the Deltas to throw off what he perceives as their shackles. All he knows is that his mother died addicted to soma, & he doesn't want the same thing to happen to everyone. In his grief, he forgets that the Deltas lack the intelligence to comprehend his message.
Needless to say, the police are called in, & they quickly get to work. They pump soma into the air, and bring water pistols filled with sedative. The people fall to the floor, at which point the Voice of Reason begins to speak from the Synthetic Music Box about peace and happiness. Predictably, everyone begins crying and hugging each other. Finally, all the Deltas are sedated and gone. But John, Helmholtz, and Bernard are arrested. Of course, utopia is fine and good, but every once in awhile a demonstration of force is needed to keep everyone in line.