Police on Wednesday demolished more than 50 stone crushers operating illegally in Bihar's Rohtas district."It was part of action against the stone-mining mafia," a district police official said.Agitated over the action, a group of supporters of stone-crusher owners hurled stones at the raiding police team and tried to disrupt the demolition drive, the official said.Superintendent of Police M.S. Dhillon, who led the raid, said the stone crushers were located in Gopibigha village. Crusher machines as well as generators were seized during the raid. A large number of illegal stone crushing units operate in Rohtas and are also involved in illegal mining in protected forest areas.