Detach yourself by observing the anxiety - rate the anxiety on a scale of 1 to 10, and watch the numbers rise and fall. Accept this temporary anxiety and don't feed it by struggling. Wait it out. Remember that it is self-limiting. It always stops.
Catastrophic thoughts increase the intensity of the attack.
I have survived this before and I will survive this again. These are just thoughts - not reality. Repeat the above steps as often as necessary. Remember that every panic attack is an opportunity to learn to manage your anxiety and fears. When the panic subsides, think about what you will do differently if you should have another attack.