Santos and Co. sold an equipment to the defendant Burgos for P100,000 payable in quarterly installments of P10,000 each. The equipment was made security for the debt. Shortly after delivery to Burgos, the equipment and the money for its quarterly payment were both lost in a fire which completely demolished the company's building. Is the buyer still liable? Why? If yes, when should he pay? Give the right/s of the creditor.