SINGAPORE - He was having his breakfast at a hawker centre in Clementi last Wednesday morning (June 20), when he suddenly heard a loud "plang" sound.

When full-time national serviceman Koh Zhi Hao, 22, turned around, he saw a man in his 40s shaking uncontrollably on the ground, with eyes shut and saliva flowing out of his mouth.

The man was believed to have suffered a seizure.

Third Sergeant Koh, who currently serves on the Singapore Navy's patrol vessel RSS Daring of 182 Squadron, saw there were about 15 people in the hawker centre, but sensed that no one intended to step forward to help. He immediately rushed to the man and called 995.

On the advice of a medic on the phone, 3SG Koh tilted the man sideways to let him breathe, and continued supporting him alone till the ambulance arrived five minutes later.

The Singapore Civil Defence Force confirmed that it responded to a call for ambulance assistance at Block 726 Clementi West Street 2, and said a man was taken to the National University Hospital in a conscious state.

Disappointed by the lack of response from onlookers, 3SG Koh decided to share his story on online forum Reddit, under the title "Your hesitation can kill/save someone", in an attempt to encourage the public to render their assistance in such cases.

His actions were widely lauded on the forum. His post drew more than 100 comments praising his quick thinking.

"I was quite appalled by the lack of willingness to help, and I wanted to inspire people through my Reddit post to be more proactive and to adopt a more inclusive thinking," said 3SG Koh.

"I did not expect such a (big) response, but most of the posts are responders... so I guess the message resonates with them, and they know that this is a message that has to get out."

Among those who lauded his actions included Reddit user Darndc, who said: "As a healthcare professional, kudos and big thanks to you... what you did regardless of whether you know what to do or not is already half the work when responding to incidents like this."

Another netizen, Lawlianne, said: "Hope you get the well-deserved recognition and maybe some promotion in your unit."