Don't help them, whatever you do. There are very tiny veins inside that if ruptured could kill the chick, cripple it or cause it to go blind. If you have an incubator or heating pad place them where they will be warm--around 94 degrees but not too warm. Don't allow the eggs to change position or the chick may forget where it is and never make it out of the shell.
A hen will leave her nest if the eggs are hatching at the same time. It is normal. The drop in temp. helps the baby to hatch properly. If she is gone after you check back in say, 15 minutes, you will need to keep them warm. If it is quiet and calm in there, she should return to the nest. She may just be nervous because she is exposed to human contact right now. Try and give her a few quiet minutes first--she should go back to the nest.