Hundreds of thousands of people rallied in Istanbul late Friday to protest the arrest of the city's opposition mayor, Ekrem Imamoglu, defying a warning from President Recep Tayyip Erdogan that Turkey would not tolerate "street terrorism". It was the third straight night that demonstrators had rallied against the arrest of Imamoglu -- Erdogan's biggest political rival -- in Turkey's biggest street protests in more than a decade. Opposition leader Ozgur Ozel, head of the CHP which called the nationwide protests, told a vast crowd in front of Istanbul City Hall that "300,000 people" had joined the demonstration.