In summer, mountain accidents may include falls, causing contusions and open wounds; fractures and torn ligaments; external bleeding;internal bleeding in the head, thorax and abdomen; injuries to the spinal column and extremities; falling rocks causing skull injuries; and falls into crevasses causing additional hypothermia, frostbite and drowning. In winter, there are skiing accidents with fractures and torn ligaments; and avalanches resulting in asphyxia, hypothermia and frostbite. In addition, there are mountain sickness; pulmonary edema of high altitude; snow blindness; heatstroke; sunstroke; heart attack; diarrhea and vomiting; pneumonia; snakebite; drowning in torrents or lakes; and burns, explosions and cuts acquired in huts. First aid, medical support and transport to hospital may vary widely.