It was nearly 7pm on a weekday in August when emergency responders Mohamad Fuad Abdul Aziz and Syed Abdillah Alhabshee were on their way home from an interview with a radio station on emergencies and first aid.
Just as Mr Syed Abdillah was about to drive their ambulance into the Kallang-Paya Lebar Expressway (KPE) tunnel, they heard a loud explosion.
Just 30m into the tunnel, the front of a Trans-Cab taxi was engulfed in flames.
Mr Fuad, 36, an emergency medical technician at Unistrong Emergency Medical Services, said: "The first thing that came to my mind was, 'Where is the driver and are there any passengers? Are they okay?' "
The duo stopped the ambulance, helped close off the middle lane to traffic, and rushed to put out the fire before the Singapore Civil Defence Force arrived - which led to them being hailed as heroes later on social media.
Thankfully, the driver had already left the taxi, although he was in a state of shock.
Mr Syed Abdillah, 37, who owns First Medic Training and Ambulance Services, said: "The ventilation system in the tunnel made it hard to put out the fire - there was oxygen. The fire was twice our height, so it took a bit of an effort to put it out. "
Some Gurkhas, who were in a van in front of them, also helped out.
Mr Fuad took a fire extinguisher from the tunnel and tried to douse the flames, but was unsuccessful as the tunnel was too windy.
Mr Fuad and Mr Syed Abdillah then grabbed the hosereel near the extinguisher and put out the blaze in 10 minutes.
They were assisted by the Gurkhas and another motorist, who helped to lay out the hose.
There was a second explosion as the duo were fighting the fire, which Mr Fuad said was due to the taxi's tyres exploding from the heat. They managed to put out that fire too.
Said Mr Fuad: "We don't call ourselves heroes. We are just normal human beings helping another human being."
Mr Syed Abdillah added: "We have been in emergency medical services for a long time. If we see danger, we go towards it. It's that sense of urgency that we feel."
