He watched as the two cyclists lay on the ground, in pain and unable to get up.
Standing helplessly by the sidelines was enough to convince him that it was something he never wanted to experience again.
So Mr Ong Wee Chee, 21, decided to learn first aid.
Mr Ong, who now works as a paramedic, is a Singapore Red Cross Society (SRC) volunteer and a First Aider on Wheels.
He said: “Every weekend, we cycle around East Coast Park and see if there are people who need help. “We give them plasters or bandage them up if they fall off their bikes.”
Saturday was World First Aid Day.
For Mr Ong, it all started six years ago, when he was volunteering as a road marshal for a triathlon.
When the two cyclists collided, all Mr Ong could do was direct the other cyclists away from the casualties while he waited for the ambulance.
He said: “I wish I could have done more, but I didn’t know what else to do.
“At that point, I had never felt so useless in my life.”
So when his friend told him that the SRC needed volunteers for an upcoming event a couple of weeks later, he jumped at the opportunity.
He said: “I decided to give it a try as I really wanted to help people.”
Mr Ong went for Standard First Aid and Automated External Defibrillator (AED) courses, which took about a week.
The courses were free for volunteers, but they had to fulfil a minimum number of duty hours.
Not medically trained
“It was tough as I’m not medically trained,” he said.
“I had no idea what the instructors were talking about, and it took me a while to understand it all.”
Thankfully, the walk-a-jog event went off without a hitch.
But several weeks later, his skills were called into action.
He was heading home from Marine Parade when he noticed a crowd gathering at the nearby junction.
Mr Ong was curious and went closer to see what had happened.
He found that there had been an accident involving a car and a motorcycle.
Mr Ong said: “Two kids had smashed glass on their faces, while their mother had a large bruise.
“And the motorcyclist was coughing up a lot of blood.”
He looked around, and didn’t see any ambulance.
“Police officers were there and had cordoned off the area, but I told them that I knew first aid, and I could help,” he said.
Together with the help of another passer-by, Mr Ong removed the motorcyclist’s helmet, and tilted his head to drain the blood out of his mouth.
The passer-by stayed with the motorcyclist, while Mr Ong checked on the other three casualties.
He said: “The atmosphere was tense. There were more than 50 people around, so there was a lot of murmuring.”
But Mr Ong didn’t let the commotion – or his nerves – get to him.
“I was really scared as it was my first time,” he said. “But if I don’t help them, who will?”
He was able to use his skills again just three months ago.
He was involved in team-building games at a sports company when he heard that one of the participants had fainted and was lying on a sofa.
Mr Ong and his colleague rushed to the man, and found that he was not breathing. They also could not feel his pulse.. So they administered cardiopulmonary resuscitation (CPR).
After about 10 minutes, they grew exhausted and asked onlookers if any of them knew CPR.
He said: “The response was disappointing, so we just carried on while we waited for the ambulance.
“His heart wasn’t beating when he was sent to the hospital, and later, I found out that the guy didn’t survive.”
Despite such experiences, Mr Ong was thankful that he decided to pick up first aid.
He said: “You’ll never know when a situation might arise.
“I’m glad I can do something to help, and not just watch on while people suffer.”
Learning first aid had an added bonus – he decided to take his knowledge one step further in 2009.
He enrolled in Nursing at ITE College East and qualified as a nurse last year.
Said Ms Serene Chia, SRC’s head of community services: “It is vital for us to have more volunteers like him.
“We are grateful to have such committed and knowledgeable volunteers, but we could always use more.”
This article was first published in The New Paper