Public Panic Attacks

Hi all, so I have a problem and need ideas and advice!

So I have Panic Disorder and panic attacks that are very randomly-occuring and severe. I could be perfectly fine one moment and the next break into a serious panic attacks that usually last up to 4 hours. During these, I shake and breath uncontrollably and I am unable to move, speak, or respond to my surroundings.

Things that help include very low outside stimulation (small spaces, darkness, no movement or noise), and things like noise and movement, especially coming towards me, make my panic attacks incredibly worse, to the point where might uncontrollably lash out in panic.

So my biggest fear is that what if this happens in public(luckily hasn't yet, but it's only a matter of time)? I'm afraid of people coming towards me, touching me, trying to communicate with me, etc, and I'm unable to communicate or gesture what is wrong and what can help me. I'm terrified of harming someone on accident, and with everything you hear about the police it scares me.

So my question is, when and if this happens, how can I communicate to anyone who sees me what is going on and what helps/doesn't help?? I want to be able to go out in public and not constantly worry about what would happen if a panic attacks strikes.

Any and all thoughts/ideas are appreciated. Thanks!!!!