When he saw a lorry crash and land on its side in the middle of Farrer Road, Mr Bai and a group of friends ran across the road to help.
But the Good Samaritan didn't see a blue sedan coming towards him, and was hit.
Mr Bai, 41, the boss of a recycling company, was sent flying some 2m, eye witnesses told evening Chinese newspaper Lianhe Wanbao.
The witnesses said Sunday's impact left Mr Bai unconscious for about five minutes before his friends managed to revive him.
Mr Bai later told Lianhe Wanbao: "We were careful when we crossed the road. Only when the cars had stopped or slowed down, did we cross the road, but a car suddenly came up from behind and hit me."
The driver, a woman, got out of her car.
She looked shaken by the accident and stood by herself by the roadside, the witnesses said.
The earlier accident involving the lorry happened when a grey sedan shot out suddenly from a side lane onto Farrer Road in the direction of Holland Road, witnesses said.
The lorry driver swerved to avoid the car, but lost control of his vehicle, which flipped onto its side in front of the Spanish Village condominium.
The driver of the sedan told Lianhe Wanbao that the car's airbags had saved his life.
The Singapore Civil Defence Force received a call at 5.02pm about the accident and arrived at the scene within six minutes, its spokesman told The New Paper.
He added that three men between the ages of 20 and 40, with abrasions on their arms and legs, were taken to Alexandra Hospital.
When contacted, an Alexandra Hospital spokesman said that the men were discharged on the same day.
The police said they are investigating the accidents.
This article was first published in The New Paper.
|He wanted to help, but gets hit by car
Click on thumbnail to view.
(Photos: Lianhe Wanbao, ST)