Police have arrested a tipper truck driver who drove off after knocking down a 81-year-old woman.

Retired nurse Chin Siat Keow, 81, was hit near the junction of Henderson Road and Jalan Bukit Merah at around 12.40pm on Saturday. Shin Min Daily News reported on Sunday that she was found unconscious, sent to Singapore General Hospital, and died from multiple injuries at about 9.25pm.

Her younger sister, Ms Shirley Chin, told The Straits Times that it is a "very tragic accident". The 63-year-old insurance agent said: "She was a very kind-hearted woman, someone who is passionate about helping people."

Police investigations are ongoing.

Road safety and heavy-vehicle drivers have been in the spotlight, after two young brothers died when they were hit by a cement mixer truck in Tampines in January.

Statistics from the Traffic Police show that heavy vehicles were involved in about 20 per cent of fatal accidents last year.