A secret society member repeatedly slashed a youth with a knife in a brawl that took place in Chinatown on May 10.
A video of the incident, which was captured on closed-circuit television, was widely shared on social media and WhatsApp group chats.
It shows two groups of people fighting in a corridor on the 16th storey of People's Park Centre, Block 101 Upper Cross Street.
The victim, Muhammed Shazryl Hykel Abdullah, 19, sustained injuries, including slash wounds on his back, and was rushed to Singapore General Hospital.
Noor Najat Alwi - one of his attackers - pleaded guilty in a district court yesterday to two counts of rioting while armed with a deadly weapon and being a member of an unlawful society.
The Singaporean, who will turn 21 tomorrow, also admitted to an offence under the Covid-19 (Temporary Measures) Act.
During the circuit breaker from April 7 to June 1, people were not allowed to leave their homes without a valid reason or meet others from different households to socialise.
The court heard that a man identified as Muhammad Roslan Mohamed Rumli, 28, and his girlfriend, known only as Kira, met another woman, called Akai, in Selegie Road on May 8.
Kira later accompanied Akai home, and Roslan video-called his girlfriend the next day. He noticed that Kira behaved "suspiciously" and refused to reveal her whereabouts. Shortly after, somebody snatched away her phone and ended the call.
Roslan called Akai, who told him that she had been with Kira at the People's Park Centre flat with a group that included Hykel. Akai claimed that one of the people in the group later chased her out of the flat for an unknown reason, and she left Kira behind.
Worried, Roslan contacted his friends, including Noor. Their group of five arrived at the flat at around 3am on May 10. Akai later texted Roslan a personal identification number to key in at the door, and his group entered the unit.
They assaulted two men who were inside, and one of the two used his phone to tell Hykel, who was out, about what was happening.
Hykel gathered his friends, and his group, which was also made up of five men, arrived at the unit at around 3.30am. A brawl soon broke out between the two groups.
Deputy Public Prosecutor Jasmin Kaur said that during the brawl, Noor slashed Hykel with a knife before fleeing the scene.
The cases involving Roslan, Hykel and several other alleged offenders linked to the case are still pending.
Yesterday, Deputy Principal District Judge Seah Chi-Ling called for reports to assess Noor's suitability for reformative training and probation. He will be sentenced on Nov 12.
