phrase requests - Expressing sudden interruption in written, narrative speech

Question: What is the lexical technique for expressing sudden interruptions in written, narrative speech?

For example:

I was walking down the street when— wait! Look at that!

In the example above, I use an em dash, but the interruption does not contain the magnitude that I was going for.

The mind almost never processes text in linearity, and this makes it difficult to create sudden events in written narrative speech.

Speaking however, is a sequential process that allows employing speech devices such as intonation and inflection in order to achieve a desired magnitude.

Is there a formal writing technique for expressing an interruption with a magnitude greater than that of in my example, in written narrative speech?

Answer

"Faster than a speeding bullet! More powerful than a locomotive! Able to leap tall buildings in a single bound!"

"Look! Up in the sky!" "It's a bird!" a woman cries. "It's a plane!" a man shouts. "It's SUPERMAN!"

The above may mean nothing at all to you, and most users, and it certainly says something about my age.

Younger users might (I hope) remember this from the early SNL (Andy Kaufman).

All that to say, it's not how you type it, it's not the punctuation you use, it's what you write that will impart impact to your dialogue.

I think the standard approach in writing to express an interruption is the em dash. If you don't think that's enough, you can go nuts.

• I was walking down the street when— wait! Look at that!


• I was walking down the street when— Holy SHIT! Will you LOOK at that!?!