It started like any Monday morning.
Mr Tien Yoon Seong and his 18-year-old son, Kang Fan, left their house in Ang Mo Kio together at 7am.
Mr Tien was rushing to drive to work in Tuas and Kang Fan, to catch his bus to Ngee Ann Polytechnic in Clementi where he was a first-year student.
"When the lift door opened, he turned left and headed to the bus stop while I turned right and walked to the carpark. We did not even say 'goodbye'," said the 49-year-old construction supervisor, as tears welled in his eyes.
As he came out of a meeting at 10.40am, he was told his son had been run over by a lorry in Sin Ming Avenue and was undergoing emergency brain surgery at Tan Tock Seng Hospital (TTSH).
Despite the operation, which lasted hours, Kang Fan never emerged from unconsciousness and was pronounced brain dead on Tuesday night.
Another pedestrian, Madam Khoo Thuan Kheng, was also hit by the lorry and died early on Tuesday morning.
The Straits Times understands the 72-year-old grandmother suffered serious fractures. She was out for her regular morning exercise and was heading home when the accident happened.
Police said they were informed of the accident involving a lorry and two pedestrians along Sin Ming Avenue towards Sin Ming Drive at about 7.20am.
The 55-year-old lorry driver, a Singaporean, is helping with investigations.
Last night, Mr Tien and his wife, Madam Lee Kim Ling, 52, a hawker assistant, were preparing to take their second of three sons off life support.
The neurological intensive care unit at TTSH was filled with friends and relatives coming to say goodbye.
Visitors fought back tears as they stood beside his bed and chanted Buddhist prayers.
Starting today, a three-day wake will be held for Kang Fan at the void deck of Block 234, Ang Mo Kio Avenue 3. He will be cremated on Saturday.
Mr Tien described his middle son, who was studying for a diploma in logistics and supply chain management, as filial and sensible.
"All my sons are no top students in class, but they are not afraid of hard work. They learnt to be independent at a tender age, as both I and my wife had to work to support the family," he said.
His eldest son, 20, is at Nanyang Polytechnic and his youngest is in Secondary 5 at Bishan Park Secondary School, the same school Kang Fan had gone to.
Madam Lee said: "We lead a frugal life. All my three children never asked me for toys when they were young. When Kang Fan grew older, he worked part time to buy the things that he wanted. He would often buy me gifts too."
Fingering the necklace she wore which was a gift from him, she said: "Kang Fan was over the moon when he made it to polytechnic. He would come home every day and tell me about his activities in school before he went to bed. He had worked part time before school started in April, to pay for his textbooks and a laptop."
Mr Tien said: "We walked through 18 years with our son. No parents would give up on their son, until the very last minute. No words can describe our pain."