In an emergency you must remember to panic!!

Well, not really, but people who *are* panicking often get really angry at your failure to panic along with them. They see your calmness not as competence in the face of an emergency, but as a "failure" on your part to "understand the seriousness" of the situation. If you're not careful (and sometimes even if you are), you can suddenly find yourself defending your actions and your attitude from a frustrated and angry person instead of solving the problem.

In my experience, the best bet is to remove the panicky people from the area where you are trying to problem-solve. This can help break the escalation of their panic (and give them a chance to calm down) and remove a fairly serious distraction while you're in an emergency situation.