She claims she had urine splashed at her face, was burned with a cigarette and beaten until she fell.
All on her first day of school this year, she said.
On Jan 2, Agnes (not her real name), 15, was picked up by her boyfriend after school.
A schoolmate, Nancy (not her real name), also 15, apparently saw her and confronted her regarding a rumour Agnes had been spreading about a mutual friend since last March.
Nancy then splashed water from a bottle at Agnes' boyfriend, who pushed her away.
At 2pm that day, Nancy contacted Agnes' boyfriend through a mutual friend on Twitter, asking him and Agnes to meet and "settle things".
They agreed, as Agnes was being harassed in school by Nancy and wanted the bullying to end.
Agnes said they met at an HDB block near a community club, where a group of eight teenage boys and girls, including Nancy, surrounded them.
One of them splashed a cup of urine at Agnes' face.
"I told my boyfriend I wanted to leave," Agnes told The New Paper.
"But he insisted that we stay and resolve the issue."
As her boyfriend walked away to call his friends for help, one of the youngsters suddenly burned Agnes with a lit cigarette.
Agnes claimed: "They burned me three times on my left arm. I didn't know what to do but moved further away."
For the next hour, the group discussed what to do with Agnes. They moved from one block to another when they saw a police car patrolling the area.
Asked why she did not approach the police, Agnes said she was afraid and thought she would get arrested.
Once the police car was no longer in sight, Nancy challenged Agnes to a one-on-one fight but Agnes did not respond.