I can't imagine hitting a person with my car and then leaving them, kid or no. I do have to say I wonder what your daughter was doing riding her bicycle in a crosswalk. Bicyclists are supposed to follow the same traffic laws as cars. Regardless, I hope your daughter is okay. That's all that really matters.
The drivers insurance should pay any medical expenses since she is guilty of hitting the girl. The driver is almost always considered at fault with a pedestrian. Not filing a police report on the injury/accident and not giving insurance info should be enough for a hit and run charge.
we have crosswalks here with no stop signs. you are obligated by law to stop for pedestrians in crosswalks but if she was on a bike then it's not the drivers fault. the fault lies with fleeing the scene of an injury accident.