At least someone - mother or father - should have made a run for it, at least tried to protect their child. Paternal and/or maternal instinct # 1 is to protect your offspring.
Made a run for what? I haven't seen a diagram or a clear picture of the enclosure. People are simply assuming that patrons (including the child's mother) had some way to get to the dogs (and the child).
Zoos are specifically designed to prevent that.