Warped/swollen wood floors

[titans]

Greeting everyone and happy labor day.
I walked into an empty house (interested in buying) and noticed in the hallway swollen /warped wooden floors. Is there reason for alarm? How much of the flooring needs to be removed to repair? I'll have an inspector take a look but came here for answers. Many thanks and suggestions are truly welcome. Could it be more humidity or a leakage somewhere in the house that caused the problem.

 

[CVrider]

I had a similar situation. It turned out there was a water leak under the house, causing the floors to swell and mold to grow and lots of mosquitos. This was not noticed by the home inspector when I bought the house. This was in Northern California, where it's low humidity most of the year.