Egypt formed a crisis unit on Thursday to investigate the deaths of Egyptians taking part in the annual Muslim pilgrimage to Mecca during extreme heat, after medical and security sources said at least 530 Egyptians had died and 31 were missing. In recent days hundreds of people from different countries have died in punishing conditions for the hajj pilgrimage in the Saudi Arabian city, where temperatures have at times exceeded 51 degrees Celsius (124 Fahrenheit). The medical source, who was with the official Egyptian hajj delegation, said the majority of those who died were not formally regist…