She was chatting with her friends at the ITE College West campus at Choa Chu Kang Grove yesterday when she noticed the people around them backing away.
Syaza Syazwani, 17, realised trouble was brewing when she saw two youths having a shoving match in the centre of the school piazza.
What happened next could have been a scene from a movie like Gladiator, in which armed men fight to the death in front of cheering spectators in ancient Rome.
In this case, one of the antagonists was wielding what looked like a long bread knife while the other was unarmed.
A crowd had even gathered on the steps surrounding the piazza to watch the two teenagers square off against each other in what Syaza called an "epic" fight.
Fortunately, no one died.
But the unarmed youth, who was dressed in black, had to be taken to hospital with slash wounds while his assailant, who wore a white top and black pants, was arrested.
The New Paper understands that the dispute could have been over a girl.
The youth in white is believed to be a 16-year-old student at ITE College West while the youth in black is said to be a 19-year-old former or current ITE student who is dating the girl.
The fight was captured on two videos, which were later posted online.
In the first video, a person can be heard describing the incident and even breaks into song at one point.
Syaza, a first-year business student, said she was at the piazza with her friends at around 12.30pm when she noticed the scuffle.
She said: "There were about 200 people in the piazza when the two guys started fighting.
"They didn't say anything, they just started pushing each other."
Students in the area gave them a wide berth, but many gathered around the steps to watch the drama.
Describing the fight, Syaza said the youth in black fell during the scuffle but got back up and tried to continue fighting against his assailant.
"The guy in white then took out a long knife and slashed him on the wrist," she added.
"It was epic. There was blood everywhere and then the guy in black ran away."
In the video clip that has since gone viral, the youth in white can be heard shouting at his opponent: "Fight? Ha? Want to fight?"
Syaza said the whole episode lasted about 15 minutes and some students tried telling them to stop fighting, but to no avail.
She said: "It kind of reminds me of the movie Gladiator.
"I was terrified, but I knew the guy with the long knife wouldn't go after anyone. He was only aiming for that one guy."