The imbedded practice of the first engine company stretching a line to the seat of the fire is very likely not to be successful. Occupants fleeing the store will impede the two or three fire fighters trying to stretch the line. Unless the fire is right at the front door, the stretch will likely be too short. Calculate the length of a stretch to the far rear corner. Seriously consider the option of planning that the first due engine will stretch into the sprinkler siamese and pump it at the maximum pressure the system permits.
Sprinklers operating at pressures substantially higher than normal are extremely effective.
The sprinkler system is operating right over the fire. The delivery of water to the fire may be obstructed by the arrangement of stock. Some stock may be shrink-wrapped, which prevents water from prewetting exposed stock. If the fire is spreading laterally, additional heads will be opening. The additional water will support this demand.