She was at work when she received a call from the Singapore Civil Defence Force (SCDF) telling her to return home to open her grille door.
The SCDF wanted to use her Serangoon North flat to carry out rescue operations.
That was how the resident found out that her neighbour, who lives a storey below, had threatened to jump.
"I was told that he had a knife with him as well," said the woman, who declined to give any details about herself.
The stand-off yesterday, which lasted about five hours, attracted a steady stream of curious residents to Serangoon North Avenue 4.
It ended after police and emergency services acted to defuse the tension and took the man to safety.
It was classified as a case of attempted suicide, a police spokesman said.
It all started with the 42-year-old threatening to jump out of his ninth-storey flat at Block 540, residents told The New Paper.
It is believed he was holding a knife.
Then he locked himself in a room in his four-room flat and refused to come out.
The police were alerted to the incident at about 1.55pm yesterday.
By 3pm, a crowd had gathered, their eyes fixed on the SCDF team as they set up rescue nets at the rear window of the unit.
At the foot of the block was a safety life air pack.
The police cordoned off access to the ninth storey. Officers could be seen shuffling in and out of the flat.
Police also activated the Special Operations Command (SOC) team, armed with shields.
The man was carried out of the flat by the Disaster Assistance and Rescue Team (Dart) at about 7.30pm.
There were bruises on his face, neck and shoulder.
An SCDF spokesman said the man was taken to Tan Tock Seng Hospital conscious.
When the TNP team went to the ninth storey after the stand-off, seven knives and five pairs of scissors could be seen outside the unit.
They are believed to have been retrieved from the man's flat.
Residents TNP spoke to said they were unaware of the incident until the authorities turned up.
A technical adviser who wanted to be known only as BJ said: "We could hear a bit of cracking noises, as though something was falling. It sounded like glass, but we aren't sure."
Mr BJ, 32, lives next to the unit.
Some, like a student, pointed to an argument that took place on Tuesday evening. The 21-year-old, who lives on the 10th storey, said she heard a girl screaming: "Mama, don't hit didi (Chinese for younger brother)!"
This was confirmed by another resident who gave her name as Ms Tan.
The self-employed 46-year-old said she saw the argument from her 12th-storey flat opposite Block 540.
She said the argument created a ruckus and police had to be called in.
The man is believed to be the father of a boy and a girl who are of schoolgoing age.
Mrs Rose Ng, who lives on the seventh storey, said she greets the family occasionally.
When asked if she noticed any problems in the family, the 59-year-old said: "They seem like a normal family. They are usually quite polite. How could (the incident) have happened?"
The police spokesman confirmed that the man has been arrested in relation to the case.
This article was first published on April 28, 2016.
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