The fire was reported at 2:48 p.m. and it took firefighters about 45 minutes to knock it down. Authorities closed down the streets around the church for hours.
The church has a food distribution program and is 90 years old.
Battalion Chief Lisa Baker later confirmed it was "pretty much a total loss" and that it caused $900,000 in damage to the church. Firefighters stripped ventilation holes in the roof so they could attack the fire from inside, but the large amount of timber in the church made the fire burn fast and hot.
One firefighter suffered a minor injury and was treated by paramedics at the scene. The cause of the fire remains under investigation, but Baker said it is not considered suspicious at this point.
"It caught on the pole and the fire traveled up the pole," said witness Kevin Carlos-Valentino who took a photo of a ball of flames that was about to engulf the utility pole in front of the church. "And you saw the transformer explode. The transformer fell to the ground and the firemen scattered when the transformer fell and all the wires fell. When the wires fell and hit the water, the wires were hot and all of sudden we lost all of the power in our neighborhood."
At one point, PG&E says almost 2,000 customers in the neighborhood lost power, but service is fully restored now.
The pastor's wife says the church was built 97 years ago by members who were electricians and carpenters.
"We had a lot of historical mementos in this church. Pictures and items we will not be able to replace," said Pauline Williams, the pastor's wife.
Now investigators are looking closely at the transformer. A neighbor told the church bishop it had problems around 11 o'clock Monday morning.
"And he said, 'Bishop, you know the transformer on the pole sparked and exploded really loud and we came out running,' and he says, 'We saw the sparks,'" said Bishop James E. Watkins from the Church of God in Christ.
Church leaders say they will rebuild.
Bay City News contributed to this report.
