A drone outfitted with heat-detection equipment played a key role in helping authorities assess the situation.
RELATED: Thousands evacuated after vault fire prompts threat to gas line in Bay Point
The Pittsburg Police Department's drone team shot the video, saying at one point temperature reached 400 degrees in the vault.
"That drone is capable of detecting heat source and gives temperatures, said Lt. Paul O'Mary with the Contra Costa County Sheriff's Office. "We utilized that last night to fly over the vault and get temperatures to help Chevron and Con Fire determine what was actually going on there."
The incident prompted 4,000 people to evacuate in Contra Costa County.