Every one of our instructors started off with "We usually work up to this over several months, but you will do it all today." That should have been a clue.
We had a class on room clearing, then we were split into 4 man teams and 12 man squads. We practiced for about 3o min, then went through two small test houses.
The final 'test' had us operate as a whole squad- which we had yet to do- to clear a 2 story building. Wax/rubber bullets added realism. The results were sobering.
Our 12 man squad took 50% casualties, 2 of which were fratricide. 3 out of 4 leaders became casualties. The actual OPFOR of 2 aggressors and 4 paper targets were subdued.
While the medical care for our many injured was good, there are some things that are best left to the combat arms professionals who do this type of thing all the time.