Emergency services are currently attending to a crash in St Clair, with two trucks and four cars involved.
The multi-vehicle crash has left a number of patients needing medical assistance, with NSW Ambulance confirming that a baby has been injured.
An ambulance helicopter and four ambulance crews are on the scene.
Mamre Road is closed in both directions in St Clair at Banks Drive.
Southbound traffic is being diverted into Banks Drive, while northbound is heading into Solander Drive.
Motorists are advised to allow additional travel time as heavy traffic is already forming in the area.