Updated at 6.03pm:
Some 15,000 people - most of them elderly - gathered at a Tze Wan Shan playground overnight for traditional free rice handouts, local media reported on Tuesday.
The handouts are an annual ritual of Yu Lan - or the 'Hungry Ghost Festival' - believed by Chinese to bring good fortune.
At least 11 people were injured or fell ill when the crowds surged forward after the gates to the playground were opened on Tuesday morning, local radio reported.
Local TV news showed dozens of elderly people falling to the ground and a girl crying as police officers struggled to maintain order.
At least two people were hospitalised. Others received medical treatment at the scene.
Police said the injured were aged between 15 and 85.
An elderly woman told local TV news she had queued for the free rice because she had no money to buy food.
Another 75-year-old woman, surnamed Wong, said she had attended several rice handouts this year.
Ms Wong, who brought a stool so she could sit and wait overnight, told TV news chaotic scenes often occurred at rice handouts.
The organisers had planned to distribute 15,000 bags of rice. Those aged 70 could get 'Lai See' lucky money of $100 in addition to a bag of rice, the organisers said.
Yu Lan is traditionally celebrated with Chinese opera performances, burnt paper offerings and prayers in remembrance of ancestors. Rice is commonly handed out during the festival in summer as a mark of respect for the poor.