Is there a word to describe the feeling of being transfixed out of horror?

Could not find an existing duplicate question, but this may be due to not know how to describe the word/feeling!

For example, given the following sentence:

Francis could not look away from the blood-drenched vampire. The blood-soaked clothes and shimmering fangs were X

And X is specifically drawing upon the fact that the appearance is horrifying, horrible, scary, etc.

Similar words that come to mind but are generic in their motivation: hypnotic, transfixing

First question on this Stack so apologies if poor formatting!

Solution 1:

According to the Oxford online dictionary the verb to petrify means by its primary definition

Change (organic matter) into a stony substance by encrusting or replacing it with a calcareous, siliceous, or other mineral deposit.

However it has the secondary, originally metaphorical, definition of

Make (someone) so frightened that they are unable to move

The the present paticiple of to petrify is petrifying which would fit well into your sentence.

As in:

The blood-soaked clothes and shimmering fangs stunned him.

stunned TFD

to shock or overwhelm

to surprise or astound

I don't have an issue with the correct answer, but I don't think "petrifying" actually scans very well. I'm surprised nobody mentioned:

Mesmerising

Capturing one's complete attention as if by magic.
‘a mesmerizing stare’