[MNDude]

is it confirmed the young men were the ones that made the tunnels?

[Theoria]

Looks like it. Who else had the energy and such to do that, day after day? Where is the extracted material? Odd, that a cement truck would roll up and think that pouring cement in it would solve the problem. Most fixes, or additions would require a permit. No engineers or contractors present to supervise the fill in? Odd stuff all around.