After hours of battling the Sunday morning fire, officials determined mineral oil leaking from a transformer caused the blaze.
Crews from over 25 towns responded to the substation fire sometime around10:31 a.m., after a series of explosions and increasing black smoke filled the area.
The ongoing fire was finally placed under control by approximately 6 p.m.
The fire injured two firefighters and evacuating as many as 40 households for several hours.
Thousands of customers lost power for several hours.
PSE&G officials are investigating what cause the transformer to malfunction.
It is unclear at this time the extent of damages the equipment sustained.