UPDATE July 23, 2019: The American Transmission Company (ATC), which owns and operates the equipment where both fires originated, says it identified a potential problem with a component at the Blount Street substation during a routine inspection last week just days before the fire occurred.

"That component is part of our investigation," the company wrote. "We do not want to draw any conclusions until we review all possibilities."

Power has been fully restored in Madison, and ATC is working with the Department of Natural Resources and environmental contractors to clean up. The company believes the first fire triggered the second, according to the Wisconsin State Journal, and hopes to identify the cause of the blaze "with reasonable certainty" by the end of the month.

Dive Brief:

13,000 customers lost power in downtown Madison, Wisconsin on Friday morning following an explosion at a transmission substation opposite Madison Gas & Electric’s Blount Generating Station.

University of Wisconsin-Madison police later confirmed the presence of a second fire about a mile away at a different substation on North Park Street. No injuries have been reported. Police evacuated one campus building adjacent to the second fire, but allowed building occupants to return shortly after.

The fire had a significant impact on travel in the city’s narrow isthmus, with traffic lights out and multiple streets closed. The incident also coincided with an excessive heat warning, which will affect the city all day starting at 10 a.m. MG&E believes the cause was a mechanical issue , unrelated to demand on the electric system from the heat wave.

Dive Insight:

The explosion and ensuing fire occurred at the joint American Transmission Company/Madison Gas & Electric Blount Street Substation just hours before an excessive heat warning went into effect, depriving thousands of customers of power at a crucial time. City and government operations were also disrupted.

The second fire impacted transmission equipment belonging to the American Transmission Company at another joint substation nearby.

The incident initially impacted 13,000 customers, although 1,400 had power restored within two hours, according to the Wisconsin State Journal. As of 2:40 p.m. Central Time on Friday MG&E reported that 5,991 customers remained without electricity on its live outage map.

The causes of the two fires are still unknown, and there is not yet an estimate of how much damages will cost.

Two fires burning in Madison.... pic.twitter.com/xr5huCv5ZQ — Mark Gehring (@markgehring) July 19, 2019

"Staff are on-site in each of the substations, beginning the investigations [into the cause]," Anne Spaltholz, communications director for the American Transmission Company, told Utility Dive.

Government operations in Wisconsin’s capital were impacted by the blaze. Gov. Tony Evers told all non-essential state employees to go home and asked residents to avoid the city’s downtown. County Executive Joe Parisi tweeted that non-essential county services in the City-County Building, Public Safety Building and Courthouse would be closed for the remainder of the day.

The University of Wisconsin-Madison remained open, and said it was working with the city to open the Kohl Center sports arena as a public cooling space for those without access to air conditioning.

"We have no reason to believe the cause of the fire is due to excessive usage from today's high temperatures," MG&E said in a statement. ATC’s Spaltholz said the investigation would also assess whether the fires at the two substations were related.