Panic attacks aren't seizures. Panic attacks (true panic attacks) are miserable, but do not cause any physical harm. They are typically time-limited (20min). I know that can seem like forever when you're having one.. but they will and do pass. It is very rare for them to occur repeatedly in a short time span: if this is apt to happen to you, it probably already has happened to you.. and you've probably already gone for a medical or psychological evaluation.
Your best treatment if you're having one is 1)tell yourself or the victim that you know what this is.. that it is a panic attack.. and it will pass. 2)Slow deep breaths (or better yet, learn the Benson Breathing technique). I think I've described that technique in other threads here in the past.

Some medications used for panic attacks (xanax and other benzodiazepine type drugs)really aren't a good idea in an emergency because they can impair other cognitive abilities. They also do not stop an attack: panic attacks are over before these drugs can metabolize. They may prevent or reduce the severity of subsequent attacks, however. There are other drugs available for individuals with genuine panic disorder, such as Paxil (SSRI and SNRI antidepressants). No drug should be used alone without also learning the proper psychological techniques a properly trained Psychologist can help you with.

With all respect to the primary care physicians on this thread, I think the diagnosis and treatment of panic disorder should be done by a mental health specialist. 80-90% of the panic attack patients I see who are medicated by a primary care physician alone are not getting the most effective treatment we can offer them.