She had just got back from exercising and was chatting with neighbours when she heard cries for help.
When Ms Ng Yee Way, 61, went to investigate, she almost paid with her life.
A man who had just attacked another resident turned his anger and knife on her.
As they grappled, with Ms Ng fearing for her life while fending off his knife, she asked him: "Kill me for what?" Fortunately, he relented and told her she could go but she "must run very fast".
She escaped with cuts to her right palm and jaw, sustained during their struggle.
Mr Tan Ban Huat, 58, who lived on the eighth storey at Block 4, Marsiling Road, had earlier slashed a third-storey resident, Mr Abdul Majid Maarof, 62, with a chopper on Monday afternoon.
Shortly after, Mr Tan, a rag-and-bone man whom residents knew as Gemuk (Malay for fat) because of his large size, was found dead in his burning flat.
In an interview at a nearby coffee shop yesterday evening, Ms Ng recounted her terrifying ordeal.
When she and two residents went to the area where she heard the cries, she could not see anyone.
Thinking it was a fight, she took out her mobile phone to call the police. Then she looked up to see Mr Tan towering in front of her.
"By the time I realised he had a knife, it was too late for me to do anything," Ms Ng told The New Paper in Mandarin.
"He grabbed my hair and tried to stab me with the knife, but I managed to grab the handle and dodged the blow."
She said the two residents who were with her ran away instead of going to her aid.
During the struggle, Mr Tan pushed her to the ground and tried to cut her neck with the knife.
"I resisted and pushed back, but I could feel he was still trying to cut me - he was making a sawing motion with the knife. Then he hit my head against the ground," she said, adding that at this point, Mr Tan paused for a moment.
"That's when I started talking to him and said, 'Why are you hitting me and trying to stab me?' He asked me why I was being a busybody and had to interfere with what he was doing."