THE Pat Sin Leng blaze began close to where the school children stopped for a break, the forensic investigation has revealed. But no cigarette butts, or bottles which could have magnified the sunlight to spark the initial flames, were found, leaving the cause of the hill fire 'a matter of speculation'. The government laboratory will pass on its findings within about a week to the investigation team which is compiling a draft report on the tragedy. But the forensic work has not shed any significant light on the cause of the freak fire, which claimed five lives. The fire raced up a steep track behind a group of school trekkers, overtaking pupils. Chief chemist David Clarke said: 'There was no petrol or kerosene there, and nothing to find it had spontaneously broken out. For example, it was thought broken bottles might have been to blame. But nothing could be found. 'A lot of cigarette butts were found on the path, but not in the area where we are pretty sure it started, which was close to where the party had been resting. 'The cause of the fire is a matter of speculation.' Deputy Chief Fire Officer Kwok Jing-keung, who heads the inter-departmental team, said he was waiting for the forensic report and post mortem reports to complete his own draft report. The three children and two teachers from Fung Yiu King Memorial Secondary School who died were honoured yesterday at a tree-planting ceremony followed by the unveiling of a plaque in their memory by Governor Chris Patten. A sombre Mr Patten, joined by his wife Lavender at the Spring Breeze Pavilion memorial poignantly spoke of the community's 'lasting duty to the parents, families and friends of those who died to be assured of our loving care and our respect for their feelings. 'They have a need for our love, and we have a need to give love, for it is only by love that we live, and only the love we have for others that lives after us,' he said. Mr Patten praised the bravery of teachers Wong Sau-mei and Chau Chi-chai who died trying to lead students to safety, and older students who put the lives of younger pupils before their own. Afterwards he told the school's headmaster Hui Wing-ho, he too had known what it was like to have somebody close to him burned in an accident, albeit not so severely. Mr Hui later said: 'I'm not sure if he meant somebody in his family or a friend. But he said he understood the care needed.' Teacher Wat Pui-yi, who had helped lead the main body of students to safety and who had tears in her eyes as she came down the hill afterwards, said: 'I think I will never forget what happened. 'What happened has forged a closer relationship between the students and the teachers.'