I'm not sure of what other ways he/they may have gotten the girls, so I've decided to work on how he/they got away without being seen. I think the easiest way would be to have a car parked down the street a bit, crossing the creek and walking through the wooded area until close to the car, and just throwing whatever he/they were carrying, jackets, etc. into the trunk and casually driving away. Even in their ride was already there, it would have taken a little while before anyone really searched for them at all.
Of course, someone who is homeless and/or a drifter may or may not have vehicle.
MOO