Scared at vs scared of

1. ?I was so scared at the huge tank when I saw it for the first time.

2. ?I was so scared at the sight of the huge tank when I saw it for the first time.

3. ?I was so scared of the huge tank when I saw it for the first time.

Are the three sentences correct English and conveying the same meaning?

I think they're all correct, though "scared at something" isn't commonly used instead of "scared of".