Considering that there are many unexploded pieces of ordnance in the area and in the tunnel itself, I think it should be considered a war grave and treated accordingly.
I am using the precedent accorded to warships that have been sunk with many of their crew entombed within the hull.
EOD is another public safety 1st responder crew like police, fire and EMS in many European cities/locales. For good reason.
“...I am using the precedent accorded to warships that have been sunk with many of their crew entombed..”
Many war graves of iron hulled ships have been “recovered” by the Red Chinese “pirates”.
https://www.wearethemighty.com/mighty-trending/allied-war-graves-off-indonesia-desecrated-destroyed/