Several pedestrians were seen crossing the road when the taxi driver crashed into them.
A woman is later pictured lying on a stretcher on the road as paramedics attend to her.
In response to queries, SMRT vice-president of corporate communications Margaret Teo said that the company was saddened to hear that one of the pedestrians had died.
"Our immediate priority is to try to get in touch with all the affected families to render assistance and support," she said.
"Meanwhile, we are extending our full cooperation to the police in their investigations into the accident."
A witness identified only as Ms Wang told Chinese-language evening daily Shin Min Daily News that there were about six people preparing to cross the road right before the accident occurred.
After they had taken a few steps, the taxi collided into two women. One of them landed on a grass patch, while the other woman lay on the road.
Ms Wang said the woman on the grass patch had head and arm abrasions, and had temporarily lost consciousness.
She came to a while later and hurried over to comfort her son. The boy had witnessed the accident and was crying loudly, said Ms Wang.
Chinese-language evening daily Lianhe Wanbao reported that photos from an eyewitness named Ms Chen showed the other woman on the road was bleeding from her mouth and nose, and appeared to be unconscious.
Earlier this month, a ComfortDelGro taxi driver
fainted while driving on the East Coast Parkway and collided with a centre divider. His passenger then alighted in the middle of the expressway.
ComfortDelGro said then that the cabby had "blacked out momentarily", and when the driver regained consciousness, he realised that his passenger had disembarked.
Emergency physician Dr Charles Johnson told The Straits Times that a sudden loss of consciousness is usually due to something that is related to the heart or the brain, such as an abnormal heartbeat, a stroke or a seizure, or a fall in blood pressure that decreases blood flow to the brain.
Some of the causes for losing consciousness while driving can be prevented while others cannot, he said.
Preventable causes include diabetes patients who do not take their medication and black out later because their blood sugar levels drop, and epilepsy patients who stop their medication and get seizures which can lead to sudden fainting.
Non-preventable causes include having a stroke, Dr Johnson added.
He said falling asleep for a short period – as short as a split second – without even realising it while behind the wheel can be life threatening, too.
This could happen if a person was tired, took drowsy medication, or was under the influence of alcohol, which affect the driver’s concentration.
"It is not a complete loss of consciousness but it is enough for something to happen during that short duration," said Dr Johnson.
Dr Goh E Shaun, an emergency medicine specialist at Raffles Hospital's Accident and Emergency department, said that it is important to get enough sleep and rest prior to any long road trip. Once fatigue sets in while on the road, it is important to take a break when convenient.
Mr Gerard Pereira, a Singapore Safety Driving Centre training manager, said that, many a time, fatigue sets in when drivers have been at the wheel for an extended period of time without a break, especially for taxi drivers whose livelihoods depend on it.
Singapore Road Safety Council chairman Bernard Tay said that one of the most important things for commercial drivers is to ensure that they are medically fit, regardless of age.
"If they are not fit, they should not be driving, as they are spending many hours at the wheel," he said.
But he added that whether a driver is about to lose consciousness is not something one can predict.
"If he is not feeling well, he should stop the car and get medical assistance and not continue with the journey," said Mr Tay, adding that this would apply to any driver.
He also said that if passengers are aware that the driver is not well, they should advise him to stop the car in a safe area, as allowing him to continue would also put them at risk too.
If the driver does black out, Mr Tay said that passengers need to consider their environment and that their reaction times might not be quick enough.
He rebuffed the idea of pulling the vehicle’s handbrake, which some netizens suggested: "If you pull the handbrake while going at a relatively fast speed, the car will spin and it is very dangerous. Any reaction to a moving vehicle must consider many factors."
Mr Pereira added that newer car models have different handbrakes which passengers might not even be able to find easily nor reach for.
Mr Tay also said that passengers could, instead, switch on the vehicle's hazard lights to alert other motorists, or try to control the steering if they can, depending on the circumstances.
But the latter is difficult unless passengers are professional drivers or are trained and have, for example, taken safety courses, he said.
Said Mr Pereira: "Whether a (passenger) is a driver will affect how he reacts. For me, I would use the steering wheel and try to bring the car to the nearest corner or wall, and try to move the driver’s right leg off the accelerator.
"But a person who doesn't know how to drive might not know that."
For motorists who encounter a driver whose vehicle is out of control, Mr Pereira advised them to slow down as much as possible, and try to sound the horn to alert the driver who might have dozed off.
