What can result in fatalities inside buildings when an explosion occurs nearby?

Flying debris and shattered glass can result in fatalities inside buildings when an explosion occurs nearby due to the sheer force and energy released during such events. When an explosion happens, it generates a shock wave that can propel debris at high velocities. This debris can include pieces of the building structure, furniture, or any other loose items in the vicinity, transforming them into lethal projectiles that can strike individuals with significant impact.

Moreover, shattered glass from windows can cause severe injuries, as the glass may scatter into sharp shards that can puncture skin and cause deep lacerations. The combination of debris and glass poses a serious risk of injury to anyone within the building, often leading to life-threatening conditions. Thus, the danger from flying debris and shattered glass greatly underscores the lethal nature of explosions, providing a clear explanation for why this answer is correct in the context of building hazards during nearby explosions.

While the other options mention critical factors like toxic fumes, thermal effects, and building vibrations, they do not capture the immediate, physical risks that flying debris and shattered glass present in the aftermath of an explosion.