In the event of a sudden water ingress, quick action is required. The leak should first be provisionally sealed with e.g. Duct-Tape and a foil or Sikaflex so that no further moisture can enter 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 components.
Provided everything has been drained and water can no longer enter from the outside to the inside, it is advisable to visit a nearby dealer who can inspect the leak and, if possible, seal it professionally right away.