I didn't witness any of the excitement of the day, but I sure heard about it!
The bird that had been using the roofs of buildings on the two blocks near the nest, learning who to land and explore, decided to go over to 205 West End Drive. Mid-morning it landed on a car, had troubles landing in a tree and it was "rescued" by folks thinking the bird was going to get into traffic.
In general, you should only intervene after getting permission for a licensed rehabbed. Too many birds get "rescued" and then have to be returned to their parents. When in doubt, call your local Audubon Society or local rehabber before taking any action. Many birds get hurt by being handled by inexperienced "do gooders".
Luckily, the Wild Bird Fund, where the bird ended up, returned it to 31o West 72nd Street in the early afternoon, and the parents quickly came to be with the fledgling. So, with one bird on the nest still, everyone was accounted for.
It looks like the parents are looking to entice the fledglings into the gardens of the Lincoln Tower buildings. There is lots of green space, tons of food and the area has lots of traffic free lawns. I'm always surprised by where hawks bring their fledglings. I would have assumed Riverside Park was the destination for these young hawks.