Hello, this is Dr K.. Answers are not medical advice and do not constitute a doctor/patient relationship. I look forward to helping you today. This is a normal childhood phobia. Kids develop lots of childhood phobias over the years that are rarely based in reality. Parents must acknowledge the fear and help the child to resolve it. Here is a great link about all phobias with help on how to deal with them.
I hope this gives you a good start.