How does Dennis Smith use imagery in Report from Engine Co. 82?

Examples of Imagery:

"The walls are covered with cockroaches and water bugs scurrying in every direction. Some are as long as three inches, and as they scamper, the smaller ones drop from the walls. The light has surprised and confused them. I look up at the ceiling, and it, too, is a moving black mass. Roaches are falling all around us, and as they hit the floor they shoot in the direction of the coal pile as if propelled by a twisted rubber band." (76)

"There is a loud cracking noise, and the sky before us is again filled with fire. The rest of the roof has come down, and the fire is let loose from its confinement, but it won't last long. All the lines around the building are directed at the roof. The fire darkens quickly, and we know it will soon be over soon. The cold has beaten us, but we won't have to outlast it." (80)