Under investigation: Director of Buildings Au Choi-kai says damage to column C13 caused by external forces may have triggered the collapse of the building at 45J Ma Tau Wai Road.

Damage to a column caused by external forces may have triggered the collapse of the building at 45J Ma Tau Wai Road on January 29, according to a Buildings Department investigation report.

Director of Buildings Au Choi-kai today said investigations are focused on three collapsed columns situated on the ground level of the building (C11, C12 and C13).