SINGAPORE - A 16-year-old boy was playing a game of hide and seek with a friend on a rooftop garden just after midnight on Tuesday (Jan 23) when he mistakenly hopped over a wall and fell 12 storeys.

Ng Jun Hui was pronounced dead at the scene by paramedics, said the police, who received a call about the incident at about 12.30am.

His father, Mr Ritchie Ng, said the family were in bed and asleep when they heard an insistent knocking at the front door at about 1.30am.

He thought his son had forgotten his house keys, but it was the police who were at the door.

"My whole mind was blank and when my wife heard the news, she started shouting and crying, waking up my two daughters," said Mr Ng, 53.

Speaking to The Straits Times in the void deck of his Toa Payoh block on Thursday, the Grab driver he found out about what had happened from the only witness, Jun Hui's friend, who had asked him at around 10pm on Monday to go with her to the sky garden.

Both had been classmates at Guangyang Secondary School. Jun Hui had taken his O-level examinations late last year and was planning to start new studies at the Institute of Technical Education.

Neither lived at Block 79D in Toa Payoh Central, but Jun Hui had been to the sky garden a few times.

When he heard that his son was not at home, Mr Ng asked his wife, pre-school teacher Amy Wong, 47, to call and check on him as he had been out the whole day with friends.

"'Don't worry mummy, I'll come back for dinner, just keep the food for me' - that's the last thing we heard from him," recalled Mr Ng, while Ms Wong sat distraught throughout the interview, holding her head in her hands and rarely speaking.

The couple have two other daughters, aged 14 and 17.

Mr Ng was calm as he described his son as a "compassionate" person who would help his classmates if they needed it.

Jun Hui, who wanted to be a scientist, had planned to go to a junior college, even taking tuition for Additional Maths for a month after his O-level exams in preparation.

When he did not qualify for JC, he decided on electronic engineering at the ITE instead.

The family held a wake for him until Thursday.

Mr Ng hopes CCTV footage would shed light on how his middle child died.

He also plans to go back to the 12th-storey garden on Saturday to see if it is lacking in any "security and precautionary measures".

Mr Ng plans to alert the authorities at Guangyang Secondary and Beatty Secondary, as well as members of parliament and the HDB, if there are safety measures lacking, such as barriers, after viewing the CCTV footage.

He wants to prevent another tragedy.

"Hopefully this can help to save lives... it's really very painful to go through the whole thing," he added. "I don't want other parents to suffer the same fate and agony."