A transformer at a Salt River Project substation in Avondale exploded into a fireball Wednesday morning.

A plume of thick, black smoke was seen for miles.

[SLIDESHOW: Fire at SRP substation in Avondale]

The facility is located at 119th Avenue and Lower Buckeye Road.

SRP spokesman Scott Harelson said a 27,000 gallon tank of mineral oil that keeps the transformers cool was burning.

He described the fire and smoke as "non-toxic."

It wasn't clear yet what caused the mineral oil to catch fire.

Our news helicopter above the scene showed the fire was confined to the one transformer.

Firefighters were seen waiting to enter the substation until it was deemed safe. SRP linemen had to first reroute electricity before allowing fire crews to enter.

No outages were immediately reported.

Once it was safe, firefighters used to foam to extinguish the flames.

SRP was assessing damage and helping fire officials determine a cause.

Harelson said the substation imports power from suppliers outside the SRP system. He added there's no indication that the fire will cause a supply problem for the utility.

Transformer fire update 2: Mineral oil burning not considered hazardous. Those with breathing issues should avoid the smoke, stay indoors.— Salt River Project (@SRPconnect) June 1, 2016
Avondale transformer fire update 1: Crews on scene. No reported injuries. Electrical system stable. No outages expected throughout the day.— Salt River Project (@SRPconnect) June 1, 2016
No outages reported due to fire at W. Valley Rudd substation. Crews on scene, working with Avondale, Tolleson fire depts. Updates to follow.— Salt River Project (@SRPconnect) June 1, 2016

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