In order that the common carrier may be exempted from responsibility, the natural disaster must have been the proximate and only cause of the loss. However, the common carrier must exercise due diligence to prevent or minimize loss before, during and after the occurrence of flood, storm or other natural disaster in order that the common carrier may be exempted from liability for the loss, destruction, or deterioration of the goods. The same duty is incumbent upon the common carrier in case of an act of the public enemy referred to in article 1734, No. 2.