Package delivered to buyer damaged

I am the seller. I had a package delivered to a buyer that was completely destroyed and dripping wet. I did package in a plastic bag as well but the water entered the bag.

They post office also out one of those we care slips in the package. Can the buyer request a refund thought what not due to the post office handling or should I just refund the buyer directly?

If the buyer rewrite help with the order though what not will if cause a defect for me as the seller ?