Frostbite -_-

When the temperature gets too low the blood vessels close to the skin start to constrict as way to keep warm. when the body is exposed to the cold for a long period this method can reduce blood flow to some areas of the body. these are dangerously low levels that it results int he freezing and death of the skin tissue in the effected area. This is how frostbite occurs on the body.
To treat frostbite, physicians,wrap the frostbitten victim in blankets to warm them and/or move them to a warm environment. also they may put the frostbitten part into warm water to help the blood flow increase and move back to the core. if there is infection or gas gangrene in the frostbitten area amputation may be necessary.

http://www.emedicinehealth.com/frostbite/article_em.htm