This is what can happen when a kitten has kittens. Her motherly instincts have not fully matured so her timing is off. Moms begin to gently bite and kick their babies as a form of discipline and to teach them manners, but she is a week or so early.
They are too young to eat on their own for another 3-4 weeks, so they need to continue nursing mom. Gently but firmly tell her no and stop her for now when she does this. And set a spay appointment for mom to be fixed in 4 more weeks when the kittens will be 6 weeks old.
Mom may go into heat before then, so do not let her out or around intact males until she is spayed!
They are too young to eat on their own for another 3-4 weeks, so they need to continue nursing mom. Gently but firmly tell her no and stop her for now when she does this. And set a spay appointment for mom to be fixed in 4 more weeks when the kittens will be 6 weeks old.
Mom may go into heat before then, so do not let her out or around intact males until she is spayed!