Baby, toddler injured in Sydney bus crash

A baby and a three-year-old have been taken to hospital in a serious condition following a bus, truck and car crash in Sydney's west.

The young children were passengers on the bus when the crash occurred in Smithfield just after 11am on Wednesday.

Five adults also suffered minor injuries and are being treated at the scene.

NSW Fire & Rescue crews are mopping up the diesel spill at the Victoria Street crash site.

The bus driver has been taken to Liverpool Hospital for blood and urine testing and the truck driver was treated at the scene before being tested.