premise: While the riots and violence in Mar del Plata were yet to be put under control, hundreds of protesters took to the street in downtown Buenos Aires.
  Several stores and commercial institutions were set ablaze and seriously damaged.
  Police detained a number of demonstrators to prevent the situation from swirling out of control.
  No death was reported so far.
  US President George W. Bush, who arrived here Thursday night, was attending the two-day summit which will be focusing on topics like free trade and fighting poverty.
   What could be expected to happen after George W. Bush attends the summit?
hypothesis: swirling out of control