Investigators say the substation holds about 30,000 gallons of oil. It's unclear how much of it has already burned off.

Crews have not determined the cause of the fire and are working to restore power to affected customers, officials with Oncor said.

An explosion at a power substation in North Fort Worth resulted in a massive fire on Wednesday evening and the voluntary evacuation of nearby homes. The incident off Seventeen Lakes Boulevard and Henrietta Creek Road was reported at about 7:15 p.

Emergency crews responded Wednesday evening to a fire caused by an explosion at a power substation in North Fort Worth. (Video courtesy of Steve Austin)