POLICE have arrested five runaway Vietnamese inmates from the Tai A Chau detention centre with the help of a thermal imager. The group was believed to have raided three village families on Lantau on Wednesday night. The deputy commander of Marine Islands District, Superintendent Len Sayer, said the five, aged between 17 and 30, were found in an inlet covered with thick undergrowth at Lo Kei Wan, south Lantau, early yesterday. ''We believe we have got all the men allegedly involved in the robbery at Shui Hau Village on Wednesday night in which some eggs were snatched from one of the families,'' he said. ''We were concerned about the incident because we were told some of the men were seen armed with pistol-like objects.'' During the raid officers seized an imitation pistol, three knives, three choppers and two home-made canoes. ''We are very thankful to the Royal Hongkong Auxiliary Air Force, which helped identify the hide-out in darkness with the use of thermal imager erected on the helicopter,'' Superintendent Sayer said. He suspected the Vietnamese had used makeshift canoes to escape from the detention centre. Also found near the hide-out were old quilts, plastic bags, tooth brushes, toilet paper and noodle packets.