A calm demeanor is essential for all agents to cultivate during times of crisis. This means that we do not run around like chickens with our heads cut off -- we are fast and efficient as necessary but we do not bark orders to those around us. By speaking to people directly with eye contact, not yelling but calmly stating all needed pieces this helps others to model that same behavior and stay calm when a cool head is needed.
I first learned these skills as a chaplain and crisis counselor with the American Red Cross where I was trained to go in after fires and disasters to work with displaced families. As I have had to practice these skills with large groups of people during major disasters I work with each individual to help them not only stay calm for their own family but also for all those around them. Both calm and hysteria will rapidly take over a large room so seeding that awareness and asking others to also share it helps tremendously with managing large groups during a crisis.