I know what you are experiencing right now, it's scary. The tightness in your chest, racing thought, heart thumping and shortness of breath.. but you'll make it through, you always have and you always will.

Recognise that you are having a panic attack, it may feel much worse, but it will pass if you learn the signs. 

Focus on the shape as it expands, try to breathe in time with the shape. In and out. Slow breaths in as the shape expands and a slow breath out as the shape deflates.

Try to clear your mind, you are inside your body looking out, not outside looking in. 
Let any thoughts slip away. There is no noise, no one around. Focus on your breathing and nothing else

You've got this. 

The panic will stop and you can begin to focus on your surroundings, you may feel tired afterwards. Don't forget to recharge and rest.

You should not ignore panic attacks so please consult a doctor if you are regularly experiencing them.