( I am sorry if this takes a bit longer I haven't been able to practise my English the last few years.)
The mine went deep into the earth, but until recently nothing unusual had occurred. But then while working in a small Tunnel one of the Workers hit the Rock, and a hollow sound followed.
Further investigations led into a Labyrinth of Tunnels. The Workers decided it was Time to call their Masters, this place was strange to them and they were afraid to go any further.