At least 40 people have been killed as a gold mine caved in on Sunday in northern Afghanistan, authorities said.Ten others were injured in the incident, which happened as they searched for gold in the Kohestan district of Badakhshan province, Afghan parliament member Fawzia Koofi said in a statement, CNN reported.Provincial official Nek Mohammad Nazari said all of the victims were mine workers.Earlier reports quoting provincial head of Natural Disaster Management Authority Sayed Abdullah Hamayon Dehqan said several people were killed and injured as a landslide hit Kohistan district."The tragic incident happened around 10:30 a.m. local time in Shipo area of Kohestan district when more than 50 people were busy in illegal digging of a gold mine there and almost all of them were buried alive and so far 20 bodies and seven injured persons have been discovered," Dehqan told Xinhua.Rescue operation for discovering the remaining people was going on, the official said, adding the number of casualties might go up.In the insurgency-plagued Afghanistan where the central government's control is poor especially in the rural areas and countryside, illegal armed men are often involved in illegal digging of natural treasures including gold, coal and lapis lazuli.