A total of 16 men were sent to two hospitals, after an accident along the Ayer Rajah Expressway between a car and a lorry on Wednesday night.
The Singapore Civil Defence Force was alerted to the incident which happened just before Jurong Town Hall exit in the direction of the city, at 8.56pm.
The first of four ambulances arrived within five minutes of the call, and no critical injuries were observed on site, an SCDF spokesman said.
Of the 16 casualties, four were conveyed to the National University Hospital, while the rest were sent to Alexandra Hospital.
All of them were conscious when they left the scene, the spokesman added.
The Straits Times understands that most of the men were workers travelling in the lorry.