Oh poor babies - lol - I watched Smokey do something similar a few weeks back. I rushed out there during a torrential downpour and ran around gathering babies & mommas to force them into the coop early. Took FOREVER to catch the little buggers and mommas kept jumping back out of the coop! Finally closed it up with everyone inside and rushed to the house. Twenty minutes later the sun was shining and a few of the pullets were peeking out the door like "hey let us out of here!" I kept them in until morning - just in case it started raining again. haha.
Well, it turns out my hen is great at sitting on eggs, but a dumb mother. She took the chicks out of the nest less than 24 hours after hatch. She kept them in the coop run, but we are having a severe thunderstorm and she did not take them back into the nest. There is water ponding in the run, and she is still sitting there in the middle of run with the chicks under her. Once the lightning stops, I will go out an see if the chicks are still alive. If so, it looks like I will have to lock her up with the chicks, at least for a week.
Cindy