Relatives were mourning yesterday after an 11-year-old boy plunged to his death from an 18th-floor flat while playing at home alone. They arrived at the ground floor of the Tuen Mun block of flats for a brief ceremony to 'pacify the ghost' of Lau Foo-tat. His mother wailed as she burned incense and paper offerings: 'Do not play around down there in the after life. If you are scared, come back and tell mum.' The schoolboy is believed to have fallen from a window while playing alone in his 18th floor flat at block four of Prime View Garden on Monday night. He was found dead on the roof of a meter-room by a passer-by. Most neighbours yesterday seemed oblivious to what had happened barely 20 hours before. They walked past while the rite was held, without offering a word of comfort to the family. A handful of curious residents gathered at a playground outside the block. Some stared silently at an open window in the unit. Some said the boy had liked to fold paper planes, set them on fire and toss them out of windows. He had been warned by police for throwing burning paper planes into flats on lower floors. At least three children have fallen to their deaths this year after being left unattended at home.