Final answer:
Fire escapes or external stairs are secondary routes that are crucial during emergencies when main exits are blocked. They must be safely constructed and easily accessible to serve as effective means of egress.
Step-by-step explanation:
Fire escapes or external stairs are considered to be a secondary part of the means of egress in a building. The tragic situation described underscores the importance of these structures for safety and as a means to exit during emergencies. When the main paths of egress are blocked or inaccessible, such as in the case of a fire, these secondary routes become lifesaving paths. Building codes now require these external escapes to be well-constructed, easily accessible, and compliant with safety standards to avoid previous disasters where insufficient egress led to the loss of lives.