Around 4,000 people have been evacuated from approximately 1,400 homes according to authorities.
Those living in areas from Baypoint by North Broadway to the West, Summer Way to the East, Suisin Avenue to the North and Willow Pass Road to the South should evacuate and plan to be gone overnight say officials.
Currently, there are two evacuation centres, Calgary Temple Church and Bay Point Bart.
Contra Coastal Fire (ConFire) has shut down the railway in both directions.
ConFire Battalion Chief Jim Huntze said the fire erupted along railroad tracks near an underground natural gas pipeline leading from a Chevron refinery.
Several departments raced to the scene, he said.
Reports state the fire was caused by an electrical power line falling.
The fallen line then started a fire close to a valve junction on the Northern California Gas Line near Pittsburg according to official reports.
Chevron, who owns the pipeline, have representatives on the scene.
A statement from the energy corporation told of how they “immediately shut down the line and dispatched a field team to investigate,” alongside beginning emergency response procedures.
ConFire took to Twitter to warn of the dangers around the fire.
They said: “Con Fire on scene of a grass fire that is threatening an underground gas pipeline in Baypoint, vicinity Poinsettia and Suisun Avenues.
“Evacuations within 1/2 mile of site we’re (sic) ordered in the last few minutes. Pittsburg PD and CCC Sheriff carrying out evacs.”
They added another tweet three hours later saying: “Chevron is working to reduce pressure in the at-risk gas line in Bay Point at this time.
“Evacuation orders remain in place overnight; if you need help evacuating, call 911.
“Currently, approximately 4,000 people are evacuated from 1,400 homes.”
Pittsburg police and the Contra Costa County Sheriff went door-to-door to urge people to evacuate their homes.
The Sheriff’s Office used its Community Warning System telling residents to “leave now” and head to an evacuation centre.
They were warned to take only “essential items” with them.