The warehouse roof collapsed as crews worked to put out hot spots from outside, after a three-alarm fire scorched the building near Sorrento Valley, San Diego Fire-Rescue (SDFD) confirmed.

The fire sparked around 2 a.m. in the 1100 block of Spectrum Lane in the Miramar area and continued for over four hours, said John Fisher, the SDFD Battalion Chief. People working at a produce group nearby the area smelled the smoke, saw the fire and alerted the authorities.

Within minutes roughly 100 City firefighters along with fire crews from Poway and MCAS-Miramar were at the scene, according to SDFD.

When crews arrived the fire was scorching the building and quickly developed into a second-alarm fire, said Fisher. Within an hour, it grew into a three-alarm fire.

Soon, the flames spread to the other half of the building, then nearly spread to another nearby building and some surrounding brush in the area, said Fisher.

Crews anticipated that the roof might collapse before it happened. The collapse would have been deadly if any firefighters were inside the building, said Fisher. So far SDFD have used 12 engines and one truck in their effort to put out the fire.

They worked to extinguish the flames from outside the building, which is a slower process, said Fisher. This was crucial to avoid placing the firefighters in peril, when the warehouse roof burned off and collapsed inward. They were also concerned the walls may collapse, and have positioned firefighters farther back.

Crews now have the fire under control and are working on hot spots that could potentially flare up, said Fisher. Firefighters were dumping gallons of water onto the charred warehouse building to make sure the fire doesn't start up again.

No injuries were reported from the fire but the building was completely destroyed.

The fire was estimated to have caused $3 million in damages, according to SDFD. The building was unoccupied at the time of the fire. A new business for a dietary supplement group was about to move in to the warehouse that is now ruined.

Investigators are not considering arson as a possible factor in the fire. Once the charred building cools off, a full investigation will be completed. No other information was immediately available.

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