The first human corpses I ever saw were those of a couple involved in an automobile crash. The car burned, but, thanks to the laws of physics, the bodies weren't touched. The fire department extinguished the car while the bodies were in the oxygen-depleted pocket of superheated gasses. The bodies were hairless and naked; the heat was high enough to vaporize their hair and any synthetic materials on the bodies.
The thing that almost stopped my heart was seeing that the back seat was full of children's clothing. Fortunately, there was nobody else in the car. That was over 40 years ago, and I still feel that same heart-gripping dread when I think about it. I'm quite literally back there. It's probably what a PTSD flashback is like.
I've seen worse, since (I was a Red Cross disaster volunteer), but the first is certainly the worst. The second-worst is when you realize you can treat it as routine. You may panic later, but right now, you've got a job to do.
The difficult I do immediately.
The impossible takes a little longer.
Miracles by appointment only.