Quick action is required in the event of a sudden water ingress. The leaking area should be provisionally sealed with e.g. duct tape and a film or Sikaflex so that no further moisture can penetrate into the vehicle. If wooden parts are affected, warm up the interior considerably and ensure good air circulation to get the moisture out of the room and the on-board equipment.
If everything is dry and no more water can penetrate from the outside to the inside, it is recommended to visit a nearby dealer who can inspect the leak and, if possible, seal it professionally.