First, the lorry ran over her leg and body while reversing.
Then, when the driver realised he had knocked down someone, he drove forward and the wheels rolled over the elderly woman's body again.
The 76-year-old woman died on the way to Tan Tock Seng Hospital.
Mr Chai Yam Foong, 54, who saw what happened, said: "I wish I could have done something to save her."
The accident happened at 4.45pm on Monday at a carpark behind Block 801, French Road, in the Jalan Besar area.
Mr Chai, a lorry driver, was at a nearby coffee shop when he saw the woman, whom he knew as Ah Heok, being run over by the lorry.
"I shouted at the lorry driver that there was someone standing at the end of the lorry but he didn't seem to hear me. If I had asked Ah Heok to join me for tea, or if the driver had heard me, this wouldn't have happened," he said quietly.
As the elderly woman laid motionless on the road, passers-by came forward to help, Mr Chai said.
One of them was Dr Chee Weng Sun, a general practitioner who works in the vicinity.
Dr Chee, 54, was walking to his car when he saw the aftermath of the accident and recognised the victim as his patient.
"The woman was bleeding on her forehead and side of the ear. Her blouse was slightly lifted, so I could see black marks on her abdomen," he said, adding that the marks resembled tyre tracks.
After realising she no longer had a pulse, the GP immediately performed cardiopulmonary resuscitation on her.
When she showed no signs of breathing after being defibrillated twice, Dr Chee knew the prognosis was bad.
Still, he kept hoping for the best, but the woman's relative later told him she did not make it through.
"Life is so fragile. She kept herself alive so well, over 70 years old, and everything was over for her in that few minutes when she crossed the road and a lorry came by.
"That's life, I guess. Things do happen," Dr Chee said.
TNP understands that a 59-year-old man has been arrested for causing death by negligence and police investigations are ongoing.
This article was first published on October 16, 2015.
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