A trailer and lorry collided yesterday afternoon on the Ayer Rajah Expressway (AYE) towards Tuas, near the Jurong Town Hall Road exit.
The force of the collision crushed the lorry's cabin, trapping the driver and two passengers.
Using hydraulic power tools, Singapore Civil Defence Force (SCDF) personnel extricated the three men from the wreckage.
They were taken by ambulance to the National University Hospital.
The Straits Times (ST) understands that the three men in the lorry suffered minor injuries, while the trailer driver was not injured.
Mr Sam Ng, 53, a colleague of the injured men, who had rushed to the scene told ST that he got there in time to see the last man being extricated and put on a stretcher. That man suffered a leg injury.
The other passenger, who is in his 40s, suffered a head injury.
"The passenger sitting in the middle was hurt the worst and bleeding from his head," said Mr Ng, who had been alerted to the accident by a phone call from his superior.
An SCDF spokesman said that it was alerted to the accident at about 2pm. One fire engine, one Red Rhino, three ambulances, two fire bikes and two support vehicles were dispatched to the scene.
Land Transport Authority tweets said the accident caused traffic congestion on the AYE from the Clementi Avenue 6 exit to the Jurong Town Hall Road exit.