SIX building professionals and two companies appeared in court yesterday over last year's Nathan Road demolition site tragedy in which six people were killed and one injured when a wall of the old Fortuna Hotel tumbled on to a walkway. The defendants were summonsed to South Kowloon Court under the Buildings Ordinance, which states anyone permitting demolition work in a manner causing injuries will be liable to up to three years' imprisonment and a $250,000 fine. Yesterday's defendants - Arthur Kwok Chi-shun, project architect Paul Yew Tak-yun, director and main contractor Chuk Kin-yuen, resident engineer Lau Chi-sing, foreman Loh Kim-yen, Wong Chi-cheong, main contractor Helfer Construction and sub-contractor Leung Shun Construction - pleaded not guilty to the single allegation. Helfer also denied failing to take safety precautions. Magistrate Cathie Wong fixed a hearing in the same court for March 4.