The First Person to Discover a Dangerous Situation
The person who initially discovers any type of dangerous situation must immediately take steps to insure their own safety and that of others around them. This usually involves moving themselves and others away from the hazard and/or to an area of refuge or shelter.
At the same time if possible, they must communicate the hazard to those who are nearby and then to the appropriate authorities. This should include dialing 911 as soon as possible to notify emergency responders. This is also true in the workplace.
ICs can also educate dispatchers and other call takers how to inform the general public on what action(s) to take if they are the first person to report the dangerous situation. They can also be certain that dispatchers and other call takers are collecting the critical information ICs need, including the nature of the danger, whether the danger is ongoing, whether people affected have been told to evacuate the immediate area, whether there are any injuries or victims, and whether the caller can describe conditions at the scene, even if they have left it.