Sounds like it. A shame. It just looks like human error a few times in whole set that lead this to happen. Neglect is the real cause of death here it would seem.The only way this happens is if a lot of people f’ed up and didn't follow proper OH&S. There's going to be a lot of finger pointing over the next few weeks/months.
There not going to be one person to blame for this. More a collective blame for being complacent and not doubling checking things that should be extra safe on. It will live with them forever to know if were more vigilant to safety it could have been avoided.