BELGRADE, Serbia — Heavy snowfall this week in the Balkans has closed down schools, left some remote villages cut off and disrupted traffic and power supplies in many areas in the region. Authorities in Bulgaria said two snowboarders died in an avalanche on Friday. The Bulgarian Red Cross said in a statement that their bodies were found at noon (1100GMT) on Friday in the Pirin Mountains in the southwest of the country. The statement said that the snowboarders themselves had caused the avalanche, apparently ignoring warnings and weather alerts that have been issued by the authorities after snow also caused traffic disruptions and power outages. Albania also reported a snow-related death on Friday after a power company employee suffered a heart attack while repairing damaged supply lines, according to the government’s energy ministry. That brought to at least 20 the number of weather-related deaths reported in Europe over the past week. About 2,000 soldiers and other emergency workers have taken part in nation-wide efforts in Albania to help those trapped in the snow and clear the roads to reach blocked rural areas.