About 10,000 customers lost power in New Jersey's Middlesex County on Tuesday after a fire erupted at a power substation.
PSE&G said there were no injuries; the station on Pierson Avenue in Edison, N.J., was not staffed at the time.
The utility said the fire broke out at about 4:30 p.m. and power was fully restored to all customers by 8:30 p.m.
The transformer failure was caused when a non-toxic mineral oil caught fire, PSE&G said.
Larry Mraz, who works nearby, said he heard a pop and his power went out. He and coworkers went outside to see the fire.
"It seemed to subside, and then repeatedly, it seems to explode again -- more flames, more smoke, subsides, and then pops again," he told NBC New York. "It's a pretty nasty black plume of smoke."
The substation is in an area near several homes and businesses.