A 17-YEAR-OLD boy collapsed at a Sha Tin playground after two teenagers attacked him with wooden poles, the District Court was told yesterday. Appearing before Deputy Judge Chau, Wong Ka-ho, 18, admitted unlawfully and maliciously wounding Chan Ching, then 17, on November 24, 1991. His lawyer, Mr Nicholas Barr, said Wong was serving a training centre order imposed by Sha Tin Court on April 27 for a charge of assault occasioning actual bodily harm. He urged the court to impose a concurrent training centre order. The court was told the attack happened in the evening. Chan was chatting with friends when another boy stared at him from a kiosk. The boy later left. Later, the boy returned with Wong and another person. Wong and one of the boys repeatedly hit Chan on the head with wooden poles. The three assailants then escaped. Chan was admitted to Prince of Wales Hospital with head and other injuries. Wong, who absconded while on bail, was re-arrested on April 7. He was sentenced to a training centre term to run concurrent with the one he is already serving.