Who should pay for damages to golf cart and to a fender on a truck?

At a family gathering.. a three yr. old child got on golf cart (the key was not in the ignition) and it rolled or he got it going and it struck a truck parked in yard, damaged the side of the fender, and damaged the golf cart. Thank goodness this child was not hurt just a little bump.Who should pay for damages to golf cart and to a fender on a truck?parents of the child