THE headmaster of a private girls' school who was attacked by chopper-wielding thugs in his office has spoken for the first time of the vicious attack. Lam Kan-tak, of St Too Girls' College, in Shekkipmei spoke to the Sunday Morning Post from his bed at Queen Elizabeth Hospital - his right leg heavily dressed and a bandaged right arm in traction. Recalling his horrific ordeal last Tuesday, Mr Lam, 37, said he was caught by surprise by his attackers. ''It was about 10.45 am, the security guard at the gate went to get a drink. When he returned, there were two men at the gate wearing suits, claiming they were from the Water Supplies Department and asking for my office.'' The guard directed the men to Mr Lam's office. ''They came in . . . they had their choppers wrapped in brown paper.'' Mr Lam said the attackers suddenly produced their weapons and lunged towards him. ''I shouted for help. One of my colleagues in another office made a dash for the door to call the police.'' Mr Lam recounted how he tried to fend off his attackers. ''I grabbed a chair and managed to fight them off a little.'' Despite efforts to protect himself, Mr Lam sustained deep wounds to his arm, knee and ankle and underwent surgery. During the fighting, one of the attackers received injuries to his arm. Mr Lam said he received a threatening call about two weeks before the attack. He said a letter had also been sent to him, again threatening him with violence. Police said they were still making inquiries into the incident, but declined to elaborate. Chief Inspector Tse Keung, of Kowloon West Regional Headquarters, said the case was ''puzzling.'' But he declined to say what inquiries were being made. ''It would be unfair to the school and others,'' he said. St Too Girls' College is a private school with student fees of between $17,130 to $19,350 per year. A self-governing committee, headed by a chairman, takes care of the day-to-day management of the school. A school spokesman said security had been tightened at the college.