Question 

My daughter  had her  first  motor vehicle  accident, she panicked and left  the scene of the accident. The damage to her car was minimal while  the damage to the other car is still  unknown.

Criminal Defense Lawyer, R. Christopher Simons Answer
While I cannot speak for Union, in my area, the police are usually more interested in seeing the other driver compensated than arresting the person who fled, especially if they turn themselves in. You will have to talk to a lawyer in your area to learn if this is the same in Union.