In an emergency, communication is critical. Speak clearly and concisely to those around you. Remember chaos is contagious but so is composure. It's not uncommon for a delay or a shut down as a response to disaster. Be ready to ACT and to provide clear concise directions.
Valuable moments are lost if people are milling around in confusion and panic, leaving them vulnerable and exposed. When they receive communication that is clear and actionable, however, people can quickly avoid a dangerous event unfolding.
A prepared message could be the calm in the storm as described in this great article*
ALWAYS CALL 9-1-1 FOR A MEDICAL EMERGENCY!
Make sure you know how to communicate with 911 operators and first responders.
Communicate your surroundings, situation, resources available and any injuries to the dispatcher.
Communicate with others involved in the incident, especially with those special populations that may need extra assistance. Finally, communicate with the injured.
Reassure them that 911 has been activated and that First Care Providers are present.