She was outside a neighbourhood cybercafe when she was jolted by the sound of an explosion.
Rushing to the source of the blast, Ms Mona Yakub caught a horrifying sight: A man in the opposite block falling from height and hitting the ground.
"His arm was still twitching for a few seconds before it stopped. I didn't dare to go near him, so I didn't get a good look," the 34-year-old said. She then ran back to the cybercafe and told two friends about what she saw.
Mr Jovis Teo, 22, and Mr Zaidi, in his 30s, called the police when they saw the body. Mr Teo said that the scene was a mess.
"There were many things on the ground. There were paper scattered about, a pail and even a cupboard," he recounted. The incident happened around 2.10am on Monday at Block 177, Boon Lay Drive.
The man was believed to have fallen from his one-room unit on the HDB block's 10th storey.
Chinese evening paper Shin Min Daily News reported that the man, Mr Lin Zhenying, 53, lived alone. It believed that the explosion originated from a gas stove in the kitchen.
When The New Paper visited the scene on Monday, the air near Mr Lin's unit smelled of leaked gas.
Neighbours said they heard the blast.
Mr Wee Fong Teng, who lives in the unit directly below Mr Lin's, was woken up by it.
"I heard a 'boom' and someone shouting 'Fire! Fire!' above me," the 51-year-old recounted.
On an 11th-storey unit, Ms Lisa Amren was tucking her kids into bed when she heard the explosion.
"I could feel the floor shaking a little," the 25-year-old housewife said.
The Singapore Civil Defence Force (SCDF) received two calls that night - one about the fire and one about Mr Lin falling.
Upon arrival, SCDF officers pronounced Mr Lin dead and put out the fire within 10 minutes.
SCDF said the fire is believed to involve a mattress.
Ms Sue Hoshim, 45, a housewife who lives a few units away from Mr Lin on the same storey, described him as a friendly person.
"He always gave my daughter snacks and greeted other neighbours," she recalled.
"When I heard it was him, I was shocked."
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