Burns are typically described by the mechanism that produced them and the amount of skin surface that is affected. Causes of burns include: Thermal heat sources such as hot water and fire; Chemicals, wet and dry; Electrical energy. Critical burns include: Large, partial-thickness burns that extend into the lower layers of the skin and result in blistering; Full-thickness burns that damage all layers of the skin and extend into fat and muscle tissue; Burns on the face, hands, feet, or genitals; Burns involving the airway or result in breathing difficulty; Burns involving someone under 5 years old or older than 60.