HONG KONG - Tens of thousands of people massed in the heart of Hong Kong late on Saturday to demand more democracy, as tensions grew over Beijing's decision to rule out free elections in the former British colony.The crowds swelled less than 24 hours after riot police used pepper spray to disperse protesters around government headquarters, arresting more than 60 people opposed to the Chinese government's tightening grip on the city.The unrest underscores the obstacles China faces in Hong Kong as a restive younger generation challenges its influence over the densely-populated financial hub.One protester said she had joined the protests to secure a better future for her five-year-old son, who was by her side wearing swimming goggles to protect him if the police fired more pepper spray."If we don't stand up, we will be worried about his future," said the 33-year-old woman named Li. "He can't choose his own future."The demonstrators broke through a cordon late on Friday and scaled perimeter fences to invade the city's main government compound in the culmination of a week-long rally to demand free elections. The Hospital Authority said 34 people had been treated in hospital by Saturday evening as a result of the clashes.