"paralyzed because of strong emotion" Is there an idiom or fixed-phrase which conveys this meaning?

Question

I'm looking for an idiom or fixed phrase meaning someone was paralyzed with the horror of a sight.

context:

• An old lady sees a young girl run over by a truck.
• A middle-aged man sees his neighbor's teenage son be struck by lightning.

Not looking for a single word (there are too many of them) and it would fit a sentence like "He/She became/was/got/etc______________________."

Answer 1

The idiom stop dead in one's tracks seems to fit. The in one's tracks refers to "on the spot" or "where one is at the moment"; it was first recorded in 1824.

Fig. to stop completely still suddenly because of fear, a noise, etc.
_{(McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.)}

I ​stopped ​dead in my ​tracks when I ​heard the ​scream (CDO)

The idiom is a variant of stop cold, and stop dead.

He was so surprised to see them in the audience that he stopped dead in the middle of his speech

Related to the theme of being paralysed through extreme fear are the participles frozen and froze, the verb is often used to express sudden shock, horror, motionless or panic at something, which renders the person affected incapable of taking appropriate action.
All the following examples are taken from Dictionary.com

• I froze in my tracks
• The child was frozen with fear
• My heart froze when she told me the news
• Terror froze him to the steering wheel.
• The lifeguard should have dived in for the boy, but she froze

Answer 2

Be like a deer caught in the headlights - to be so frightened or surprised that you cannot move or think.

Each time they asked him a question he was like a deer caught in the headlights.

From Cambridge Idioms Dictionary, 2nd ed.

Answer 3

To be Petrified is to be paralyzed or shocked into inaction by fear or horror.

"The old lady was petrified with horror at the sight of the girl going under the wheels of the truck."

Answer 4

terror stricken or terror-struck; in a state of terror

And exactly at the moment when the space between the wheels came opposite her, she dropped the red bag, and drawing her head back into her shoulders, fell on her hands under the carriage, and lightly, as though she would rise again at once, dropped on to her knees. And at the same instant she was terror-stricken at what she was doing. "Where am I? What am I doing? What for?" she tried to get up, to drop backwards; but something huge and merciless struck her on the head and rolled her on her back. "Lord, forgive me all!" she said, feeling it impossible to struggle

_{Anna Karenina By Tolstoy}

Answer 5

Makes the blood run cold - Fig. to shock or horrify someone.

The terrible story in the newspaper made my blood run cold. I could tell you things about prisons that would make your blood run cold.

Scared Stiff - Fig. badly frightened.

We were scared stiff by the robber. I was scared stiff when the dog growled at me.

Answer 6

Scared to death may suggest the idea of being petrified by a strong emotion:

• to make you feel extremely frightened, scare the hell out of you. David suddenly appeared like a ghost in the doorway and scared me to death.

(Cambridge Dictionary of American Idioms)