A land and air search was continuing early this morning for an 11-year-old mildly retarded boy who went missing on a hike with his father in the Tai Tam Country Park. Shiu Yik-hin vanished while his father was in a toilet at a barbecue area on Mount Parker Road at 11.45am. The father called 999 after searching for the boy for more than two hours. The pair had set off from Quarry Bay about 11.15am, walking up Mount Parker Road on the first stage of a hike to Windy Gap in Stanley. 'The boy had disappeared when his father came out of the toilet,' a police spokeswoman said. 'His father mounted a fruitless search for about two hours in the area and then dialed 999 to report to police.' Police Tactical Unit officers, mountain rescue officers from the Civil Aid Service and firefighters, helped by tracking dogs, fanned out across the area but last night there had still been no sign of the boy. A Government Flying Service helicopter was also involved in the search. Tony Ho Kai-hin, assistant police divisional commander for Chai Wan, said about 100 men from the emergency services were looking for Yik-hin in small teams at five different locations. But he said the search was difficult as the boy was autistic and might not respond to rescuers calling his name. Police said a hiker told officers the boy had been seen entering the toilet but it was not known if it was before or after his father came out. The boy is about 1.4 metres tall, of heavy build with short hair, police said. He was wearing a grey T-shirt, checked shorts and a pair of white sports shoes when he disappeared. Police last night issued a photo of Yik-hin and urged the public with information about the boy to contact police on 2813 1717. He is the third person to go missing while hiking in country parks within three months. Yuen Chi-yung, 22, who was leading a team of four female hikers as part of a weekend training course in Sai Kung Country Park, went missing on October 2. His body was found in dense bushes three days later. The other missing hiker is off-duty policeman Ting Li-wah, 45. He was reported missing on September 11 while hiking in the 7,477-hectare Sai Kung Country Park and has not been found. The missing policeman's last contact was when he called 999 on September 11 saying that he was lost. He was last seen in a Tai Long Sai Wan grocery store, where he made a call about 90 minutes before his emergency call.