Residents of Bukit Batok West Avenue 6 resting at home on the evening of Nov 6 last year were jolted by loud bangs that sounded like gunshots.
The residents peered out of their windows and saw a fireworks display near Block 194B. Some of them then alerted the police.
A father-and-son pair was later found to be responsible for the unlawful pyrotechnics display.
Cleaner Alagappan Singaram, 54, was fined $5,000 yesterday after pleading guilty to discharging the fireworks. He is the first person to be convicted of the offence under the Dangerous Fireworks Act.
His son, A. Hariprasanth, 19, who is waiting to start his national service, also admitted to a similar offence yesterday morning.
Deputy Public Prosecutor Nicholas Lim said the pair went to Johor Baru on Oct 28 last year to buy decorative and festive items for Deepavali, which fell on Nov 6.
They also bought a box of fireworks called "25 Shot Cake".
At around 7.40pm on Nov 6, the pair set up the fireworks near the void deck of Block 194B and Hariprasanth lit the wick.
DPP Lim said: "Consequently, 25 rocket fireworks shot up to a height of about nine to 10 storeys before exploding in mid-air, and lasted for about two minutes. No injury or damage to property was caused."
The duo were among six Singaporean men charged in court last November over illegal fireworks.
The other four are Elvis Xavier Fernandez, 26, Jeevan Arjoon, 29, Thiagu Selvarajoo, 30, and Siva Kumar Subramaniam, 48.
Thiagu is accused of letting off fireworks shortly before midnight on Nov 5 in Gloucester Road while Siva Kumar allegedly abetted him in committing the offence.
Jeevan allegedly let off fireworks at an open field in front of Block 504B Yishun Street 51 at around 3.30am on Nov 6.
According to court documents, Fernandez is said to have discharged a bundle of six "whistling fire sparkles" at Block 18 Joo Seng Road near Upper Aljunied Link later that day.
The cases involving these four men are pending.
Yesterday, District Judge Eddy Tham called for a report to assess Hariprasanth's suitability for probation. The youth will be sentenced on April 16.
Offenders convicted of discharging dangerous fireworks can be fined between $2,000 and $10,000 and jailed for up to two years.