Bubble, failure to stop and report an accident can lead to a six month jail sentence. However if someone died, it would surely be a lot more than that (perhaps it would depend on whether or not it was felt she could have survived the first impact). This appears to be a well known blackspot where people speed. I also doubt that the cars would not have seen her, even if the lorries didn't and the cctv appears to show adequate street lighting.
After five days, two drivers have been traced, two have not. They must surely have seen some evidence of the collision on their cars afterwards, and I find it hard to believe that a car driver at least would not feel some impact if they hit a grown adult at speed.