Three characters in three different locations at the same time.
Question: Three characters are all doing something very important to the plot at the same time. Can I swap from one location to another in order to explain what's happening in roughly chronological order?Answer:
You have to be careful about rapid intercutting. Switching points of view every few paragraphs can be disconcerting to readers. (It's a bit like trying to watch TV with a roommate who keeps changing channels just when when you start to get interested in a program.)
Usually, it is best to switch points of view at chapter breaks. This may require jumping back in time.
For instance, let's say your big event begins at roughly 7 PM and reaches its climax near 8 PM. You may start in Character A's POV at 7PM and follow him until 7:50, ending the chapter just when it's clear something dramatic must happen next.
The next chapter then switches to Character B at perhaps 7:15 PM, and you describe what happens from that character's POV (just as dramatically) until 7:50.
The next chapter might begin with Character C at 7:40, but this time you stick with that POV all the way through to the end of the climax (perhaps 8:15).
If that reads as unwieldy and you feel it's better to have these three characters act simultaneously, with no jumps in time, then you may have to simply follow one character and ignore the other two. Perhaps later on you can have them explain to the main character what they were doing while he did his part.
A third option is to give the main character some way to know what the others are doing. Perhaps they have a way of communicating, or perhaps he sees the result of something they do so he knows he can proceed and vice versa. This way you can stick with one POV and still keep the reader aware of all the action as it unfolds.
Another alternative would be to write the entire story from an omniscient perspective, since an omniscient narrator knows everything that is happening. However, the price you pay for this broad perspective is that the reader can lose the intimate connection with the main character that a limited perspective offers.