Two cars collided on Station Road in Deer Park at around 12.20am.
Three adults and three children from one were taken to hospital.
One baby has life-threatening injuries, and a second baby and another toddler have non-life-threatening injuries, as do the three adults.
The driver of the second car, a 22-year-old man from Nidrije, was not injured and was taken into custody at the scene.
