Tim was having drinks with two friends at a bar in Suntec City when they heard a loud bang.
Speaking to AsiaOne, the 27-year-old said: "We turned around and saw a crowd looking down into the [Fountain of Wealth]."
When Tim and his friends joined the crowd, they saw a car overturned at the bottom of the fountain and the driver was still inside.
The accident took place in the early hours of Saturday (July 13).
"The security guards were going around to ask who could help before the firefighters came, so we went down [to help]," Tim recounted.
"You see someone down there, you don't know if he's alive or not, so you just help out."
Without hesitation, Tim and his friends rushed down to help, along with a few other people.
"We checked to see if the guy was okay and had any injuries. When we saw that he was okay, we pulled him out," said Tim, who is trained in cardiopulmonary resuscitation.
He added that while they were waiting for Singapore Civil Defence Force (SCDF) personnel to arrive, one of the people who helped, happened to be a nurse, and checked the man for possible internal injuries.
Photos of the accident were circulated on social media.
Responding to AsiaOne's queries, SCDF said it was alerted to the accident at 3 Temasek Boulevard at around 12.20am. The police said the 56-year-old male driver was taken conscious to the hospital and "is being investigated for dangerous driving".
According to Suntec City's website, the Fountain of Wealth is "temporarily closed for maintenance" from July 5 to 25.
A Suntec City spokesperson told AsiaOne that they are aware of the incident and are "fully co-operating with the relevant authorities on their investigation".
They added that until the investigation is completed, they are unable to provide further details or comments.
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aishahm@asiaone.com