Panic attacks can have varying degrees of intensity. Usually, you become convinced or at least very worried that you’re about to die. It’s like a chain reaction of anxiety. I’ve had panic attacks where I was crying and shaking. I’ve had panic attacks where I hyperventilated and thought I was having a lethal allergic reaction and my throat would close up and I would die any moment. My last panic attack, I didn’t hyperventilate but I thought I was having a heart attack and became afraid to move, so I called an ambulance and spent 12 hours at the ER. The thing is, the symptoms of a panic attack are very similar to the symptoms of a heart attack. And your throat might feel like it’s closing up. And you might feel faint, like the world is fading away. You wonder “what if this time I really am dying?”.
And yes, one can and does lose control over one’s emotions during an attack. If you could have a say in the matter, you probably wouldn’t be feeling terrified. If you had direct control over your emotions, panic attacks wouldn’t be an issue in the first place. The thing is, we don’t generally have much control over our emotions. We have control over our actions, but our emotions come and go. This is why it’s better to accept the anxiety rather than desperately try to fight it.