OFD Fire Chief Damon Convington told KTVU that the fire was first reported at about 4:55 p.m. and was quickly upgraded to a two-alarm, then a four-alarm response.

"This easily could have been a two or three block radius fire had the crews not acted so quickly to get it under control," Covington said, adding that firefighters were still working to fully extinguish the blaze as of about 6 p.m.

OFD Battalion Chief Porya Jeddi told KTVU that an Oakland Police Department officer on scene who spoke with a tenant of the burning building learned there was a possible marijuana grow operation inside the one-story warehouse, though authorities could not comment on the legality of the operation or if it was related to the fire.

Jeddi noted that the entire warehouse was engulfed in flames by the time firefighters arrived, which he said was "not normal" for a building of that size.

"On a bigger building like this, we have some time to recover. However, upon arrival, the whole warehouse was gone," Jeddi said.

Jeddi added that the size of the fire meant responders had to switch to defensive tactics once they arrived at the scene. Firefighters focused on defending adjacent buildings that were exposed to the flames.

Jeddi added crews managed to halt the fire from spreading to nearby residential buildings, though the fire spread to RVs parked in the area and to an adjacent abandoned building.

Jeddi said more than 70 firefighters managed to stop forward progress of the fire by about 6 p.m. No firefighters or bystanders were reported injured in the fire.

The Source: Oakland Fire Department, KTVU reporting