DEVELOPING: John Pless, EPB spokesman, said there has been "a pretty significant fire" at an EPB substation off Chapman Road.
Chattanooga fire crews are currently working the fire.
Pless said around two dozen customers are still without power, and EPB cannot manually reroute electricity at the Chapman Road substation until the fire is extinguished.
Pless said there is "no idea yet" what caused the fire, but there will be an investigation.
"As of now, we're just waiting on the fire department to clear the scene," he said around 7:45 p.m. Saturday.
EPB has also lost at least one transformer to damage, Pless said.
Hamilton County dispatchers are asking motorists to avoid Shallowford Road, Jersey Pike and Chapman Road near Highway 153 and Interstate 75.
A bad transformer has reportedly resulted in widespread power outages in the area, including numerous traffic lights.
EPB crews are working to restore power, and law enforcement are attempting to control traffic.