Trapped after an accident with three lorries, the bus driver was feeling faint and could not get out.
But he was saved by a man who later disappeared from the scene.
On Wednesday evening, an SMRT bus was involved in an accident with three lorries at the junction of Sembawang Road and Yishun Avenue 7.
The 66-year-old driver of bus service number 800 found himself trapped in his seat by an iron bar that fell onto his legs, leaving him unable to move.
A passenger who wanted to be known only as Ms Caroline, 38, a housewife, told Lianhe Wanbao that the greatest damage was done to the front of the bus, which caused the driver to be trapped in his seat.
"We were all in a state of panic and didn't know what to do," she said.
"Then a man in his 40s came and prised open the bus doors from the outside and removed the iron bar which was trapping the driver. "He later left the scene in a hurry."
She said she went to help the driver, who had glass fragments all over him.
"The driver said he felt uncomfortable and dizzy," she said.
"I helped him clean up and found that his temperature was a bit high, as though he had a fever."
The impact of the accident shattered the windscreen of the bus and sent passengers flying.
Ms Caroline, who was taking the bus with her two children, said there were only 10 passengers at the time.
A spokesman for the Singapore Civil Defence Force said it received a call at about 7.30pm about the accident.
Four people, including the bus driver, were taken to Khoo Teck Puat Hospital.
"They sustained minor injuries and were conscious," said the spokesman.
Police said investigations are ongoing.
TNP understands that two of the others taken to the hospital are a 36-year-old man and a 58-year-old woman, both of whom were passengers.
As for the mysterious rescuer, there were no pictures taken of him and his identity remains unknown.
This article was first published on March 13, 2015.
Get The New Paper for more stories.