What action should be taken if an ignition source is discovered at a hazardous materials scene?

At a hazardous materials scene, when an ignition source is discovered, securing the area is a critical action to take. This involves assessing the situation and ensuring that no one enters or exits the scene without proper authorization. Securing the area helps to prevent ignition sources from causing a fire or explosion, particularly in environments where flammable or explosive materials may be present. By establishing a safe perimeter, firefighters can control access to the site, minimize risk to personnel, and allow for the proper response team to assess and handle the hazardous materials safely.

Turning off or removing the ignition source is less advisable, as it may not always be safe to do so, and could inadvertently cause a more dangerous reaction. Encircling the area with fire hoses might provide some level of protection, but it does not directly address the immediate necessity of controlling access and maintaining a safe environment. Thus, securing the area is the most appropriate response in this scenario.