local vm = VoxelManip()
	local p1, p2 = vm:read_from_map(pos_start, pos_end)
	local data = vm:get_data()
	local i
		for i, c in ipairs(data) do
			local nn = minetest.get_name_from_content_id(c)
			data[i] = minetest.get_content_id("air")
		end
	vm:set_data(data)
	vm:write_to_map()
	vm:update_map()

	vm:calc_lighting()
	vm:update_liquids()