OPEN plan designs at Vietnamese detention centres may no longer be sufficient to deal with the increasingly unstable population. Changes are expected as a result of violent scenes on Wednesday when hundreds of police and Correctional Services Department (CSD) officers rushed to High Island Detention Centre after a guard was taken hostage. Wong Fu-shing, 34, was told that unless demands to stop the Vietnamese repatriation programme were met he might be killed. Security Branch officials said the traditional free movement of individuals between huts depended on the co-operation of inmates, a point that would come under scrutiny. 'In designing the centres we very largely depend on their own self-discipline,' Principal Assistant Secretary for Security Gordon Leung Chung-tai said. 'Very obviously they are not prisoners such as you would find in other penal institutions. 'But safety measures in the camps would take this into account and we would be looking into this in light of this experience.' At the camp yesterday, a six-year-old child was dragged on to a dormitory roof in a standoff during efforts to remove people for deportation. CSD Assistant Commissioner Bonnie Wong Yuk-man said the situation was volatile. 'We are watching the situation and, yes, this is a worry.' Mr Wong was held hostage for more than 11 hours in the camp's north section after a group attempted to storm the south section. Bonnie Wong accepted there was a growing risk to officers, but said it was assessed regularly. Legislator and security panel member Selina Chow Liang Shuk-yee said more staff alone would not solve the problem. Under the present arrangement the camp is guarded by about 30 staff per shift. 'It is time to consider separate accommodation and imposing stricter measures for troublemakers. 'The time has come for a rethink,' she said. Mr Leung said the peaceful outcome of the incident, which involved lengthy negotiations, reflected well on the professionalism of staff. CSD officials believed the action was not directed against staff, but the result of Vietnamese frustration at their pending return. Prosecutions over the incident, which is under investigation, will not be hampered by the repatriation process, officials said. 'The Government's position is very clear. No one is above the law,' Mr Leung said. At least 10 Vietnamese thought to be involved in the incident were last night being kept in a separate unit at High Island. No arrests had been made, a police spokesman said.