I'm putting this under Other cause stories are meant to free you, not remind you of being caged. And articles are meant to inform you, which this may, but tend to not remind you of being caged.
With this said, this is how I'd describe a panic attack. If you do not know or understand what a panic attack is, well, it's when you panic to the point of physical symptoms.
(TW For mention of self harm-no explicit discussion, just the phrase self harm).

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Emotional View

You're filled with an impending sense of doom, almost as if the world were on your shoulders and your back was about to break, almost as if you are dying, almost as if...you get the idea. Thoughts go like bullets through you, each one making you panic more and more and more, and it feels endless, like there's no light at the end of the tunnel. Sometimes you'll see a light and think it's over, but those are the headlights of a car and you are the deer.

But there is always a final light, you just may not see it.

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Physical View

Since everyone has a different response to their triggers, it is impossible to cover every physical symptom one may experience during an attack, but I can list some common ones.
  1. Shaking, maybe to the point of almost convulsing.
  2. Hyperventilation (rapid breathing)
  3. Sweating profusely
  4. Chills/hot flashes
  5. Rapid heartbeat
 
But these symptoms will go away, with time.

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Wolves (What It Feels Like)

This is how I describe my attacks to people who don't experience them.
  There's a pack of eight wolves surrounding you. You see them, and you try to scare them off (fighting off the attack before it happens), but you fail (sometimes, not always). They start lunging at you, and you get scared (the start of the attack where you begin to feel hopeless). Soon, they sense your fear and start their attacks, biting at you (physical symptoms begin). You try to stop the blood so you don't bleed out (so you don't self-harm). But you also must fight off the wolves (fight off the attack), which tires you (drags you down a hole of more hopelessness as your efforts fail), but tires them faster. After what feels like forever, they finally go away.

If you experience attacks, you may feel different during them than I do, and that's okay.

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How To Help (Others And Yourself)
If you are a bystander:
  1. Ask them if you may touch them-they don't have to say anything, just shake or nod their head. If they say yes, put a hand on their shoulder or something to help ground them.
  2. Breathe louder if you notice hyperventilation. Breathe at a normal pace, but louder.
  3. Ask them to identify a square in the room. It could be a picture frame, or just one of the walls. Ask them to trace their eyes over the edges, breathing in as they go up and down, and out as they go left to right.
  
If you are experiencing the attack:
  1. ALLOW OTHERS TO HELP!! If you aren't comfortable with being touched, you don't have to be touched.
  2. Breathe in for 8 seconds, hold it for 4, and out for 8.
  3. Try to recognize what triggered the attack. Don't avoid the trigger, but find ways to make it so that it won't cause an attack.

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I hope this does not somehow cause offense to anyone. This was inspired by this call-to-arms.