What does the red mean?

[v0031]

What Happened in Japan That Day
The temperature near the blast site reached 5,400 degrees Fahrenheit.  The sky seemed to explode.  Birds ignited in midair; asphalt boiled.  People over two miles away burst into crumbling cinders.  Others with raw skin hanging in flaps around their hips leaped shrieking into waterways to escape the heat.  Men without feet stumbled about on the charred stumps of their ankles.  Women without jaws screamed incoherently for help.  Bodies described as "boiled octopuses" littered the destroyed streets.  Children, tongues swollen with thirst, pushed floating corpses aside to soothe their scalded throats with bloody river water.

Somehow a bit odd. I'm not sure what it means.

[Mr. Reactionary]

In the context of injuries,  raw is often used to describe exposed flesh. For example when i had the flu last month i had to blow my nose so much that the tissues rubbed off the skin beneath my nose leaving behind the sore red flesh beneath. The expression is that i rubbed my nose raw, because the flesh was exposed.

In your example, it means that the heat from the bomb badly burned these people. The burns were significant enough to cause the skin on their backs to literally peel from the body into strips, thus exposing their flesh.

To leap shrieking means to jump while yelling, because of the pain of the burns.

[v0031]

Thanks. That makes me clear.

But what does in flaps mean?

[Grumpier Than Uncle Joe]

Thanks. That makes me clear.

But what does in flaps mean?

Google "skin in flaps" and view the Google images.  Oh and as a warming, it's not pleasant.

[v0031]

Thanks. That makes me clear.

But what does in flaps mean?

Google "skin in flaps" and view the Google images.  Oh and as a warming, it's not pleasant.

Thanks. That's a good way to use google.
Is this what I want?
a flat piece of paper, cloth, metal, etc. that is attached to something along one side and that hangs down or covers an opening

[Meclazine for Israel]

Sounds like fantasy to make the story more brutal.

You would have either been incinerated or not. No question about burns but flaps around their hips appears somewhat extreme.