Put a safe boundary in place
Keep the dog and children completely separate with secure doors or gates, not just a spoken instruction to 'be careful.' Plan the household routines around the boundary: meals, toys, resting spots, visitors and busy transitions. If you cannot watch both closely, separation stays in place. Don't ask children to feed, handle or practice with the dog. Never punish a growl or snap, you need those warnings to be heard, and punishment can make the situation harder.
If a bite broke skin, the injured person should get medical advice promptly. Have your vet check your dog for health issues that may affect behavior and ask for a referral to a qualified clinical animal behaviorist. Avoid a do-it-yourself exposure exercise around children. The individual plan may involve changes to the home and adult-only training, but that needs a professional assessment first.
Give everyone a way to rest
The dog needs a quiet place where no child can reach them. Children need simple, consistent boundaries without being made responsible for the dog's behavior. A family can care deeply about its dog and still decide that safe separation is the first step. Don't promise yourself that a cue or a smaller breed makes a snap harmless.
Tonight, check every gate and door used to keep the dog and children apart, then write down what happened before the most recent warning for your vet. Do not set up another meeting to confirm the pattern.
Sources: Dogs Trust on children and dogs. Dogs Trust on aggression and safety.