A 61-year-old woman was killed when a BMW car ploughed into a lorry on Saturday morning.

Her 68-year-old husband was injured in the accident, which happened at around 6.50am along Collyer Quay, near the OUE Link Bridge.

According to Chinese evening publication Shin Min Daily News, the couple had been collecting cardboard in the area, as was their habit every Saturday morning.

The Chinese newspaper identified the elderly man as Mr Zhuang Jieyan, and his wife as Madam Chen Peiqin.

A friend of the couple's son, who wanted to be known only as Ann, said Madam Chen had been standing behind the lorry to hand cardboard to her husband, who was on the back of the vehicle, when the crash occurred.

The impact caused Mr Zhuang to fall off the lorry, fracturing his leg and causing him to black out momentarily.

His wife landed on the car's bonnet. When Mr Zhuang came to, he frantically looked for his wife. When he found out she was on the car's bonnet, he asked the BMW driver to move her to the ground, Shin Min reported.

In response to queries from The Straits Times, the police said they were alerted to the incident at 7.07am on Saturday.

The elderly couple were taken to Singapore General Hospital, where Madam Chen later died. Her husband had his injuries treated and is now at home.

"The 45-year-old car driver was arrested for causing death by a negligent act," said a police spokesman. He added that investigations are ongoing.

According to friends of the couple's son, the BMW driver was allegedly drunk at the time, although the police could not confirm this yesterday.

Ann said Madam Chen was the main caregiver for her nine-year-old grandson, who developed a medical condition following a high fever three years ago. The grandmother took care of the boy during weekdays.

She would go with her husband to collect cardboard during weekend mornings, when traffic is less heavy.

"Now (my friend) is really very lost and doesn't know what to do," said Ann. "They were all living together and he was very close to his mother."