Hong Kong’s education minister demanded a full report from City University after a giant, green rooftop at its Kowloon Tong campus collapsed without warning yesterday, injuring three people in a hall that was filled with hundreds of students taking an exam just a few days ago. The university set up a three-member committee to investigate what went wrong at its sports centre after Secretary for Education Ng Hak-kim ordered “a very detailed, comprehensive and urgent investigation of the whole thing”. Experts believed the collapsed rooftop, covering an area of 1400 sq meters, with newly-added green pitch last year, was attributed to overloading as the rooftop with a loading capacity of 73 kilograms per square metre, was about at least five times less than structurally capable of holding vegetation of at least 300 to 400 kilograms per sq metre. The legality of the green structures’ addition is also put into question as the university admitted that they did not submit any buildings plans of the structures to the Buildings Department for approval. But Cheng Ka-hing, the department’s senior building surveyor said any alterations that affect the building’s structure required the owner to submit the relevant buildings plans to the department. “It’s not illegal”, insisted Wong Ka-yu, the university’s director of campus development and facilities. “We’ve done the green rooftops all according to the building regulations. There’s no need for a formal submission.” The collapse happened around 2.30 pm yesterday at Chan Tai Ho Multi-Purpose Hall, located on the fifth floor of the Hu Fa Kuang Sports Centre with over 20 years of history, as five to six caterers were preparing for a dinner event to be held today. “Initial investigation showed that there was water leakage inside the hall. We were told that water was showering down from the roof,” a source familiar with the investigation said. “The caterers immediately ran out of the hall to seek help. Shortly security guards arrived. The roof collapsed and the air force pushed two of the security guards to the floor.” Two men and a woman were injured. Both men, aged 55 and 57, were security guards. They were sent to Caritas Medical Centre in Sham Shui Po and in a stable condition while the woman suffered a shock. In addition to the collapsed roof at the sports centre, the university has also shut down a green rooftop at Wei Hing Theatre as an “emergency measure” because both structures are similar. Herman Hu Shao-ming, chairman of the university’s council, said inspections will be conducted at buildings with green rooftops on campus. “First of all, we will check green gardens rooftops, as many of our buildings have 20 to 30 years of history already,” said Hu, after visiting the injured in Caritas Medical Centre. “We have always had regular maintenance and inspection. Now we will see if there are any spots requiring more detailed checkup,” said Hu. Green roofs, at present introduced to four buildings on campus, are part of a green initiative advocated by Chief Executive Leung Chun-ying when he was a council chairman in 2008. The committee, comprising vice-presidents Sunny Lee Wai-kwong and Professor Horace Ip Ho-shing, and chief-of-staff Professor Paul Lam Kwan-sing, is expected to deliver a report to the Education Bureau within two weeks. The committee will also include a structural engineering expert and two student representatives.