That huge General Electric Industrial Plant fire in Louisville Kentucky

[Cooley Hurd]

4. Ironically, toasters...

I'm kidding, of course. Here's the breakdown of the industrial park per Wikipedia:

https://en.wikipedia.org/wiki/GE_Consumer_%26_Industrial#Appliance_Park_production_operations

In 1951 construction began in Louisville, Kentucky on Appliance Park, the 1,000-acre (400 ha) manufacturing facility that would eventually employ 25,000 full-time employees. At the start of the park, Appliance Park was a self-sufficient city that provided for its own needs, right down to mail handling (until recently, Appliance Park had its own post office, staffed by United States Postal Service employees, to handle the complex's high volume of mail). In fact, Appliance Park was such a large and self-sustaining facility that the Postal Service granted Appliance Park its own ZIP code, 40225, in 1952.

Building 1 (AP1) was opened by late 1951 with washers and dryers being manufactured in the 10-acre (40,000 m2) building. AP1 was the location of the world's first non-government used computer that was stored in what is today the GE Industrial Data Center. In 1953, Appliance Park Buildings 2 through 6 were finished, beginning large-scale production at Appliance Park.

Building 2 (AP2) made ranges and ovens until 2000, when GE moved production to Roper Corporation. Currently, AP2 houses operations to support AP3 and is the home of the GE Geospring high-efficiency water heater.

Building 3 (AP3) currently makes dishwashers. Hotpoint, GE Profile, and GE Monogram models are all made here. AP3 makes up the largest percentage of Appliance Park employees, with over 1,000.

Building 4 (AP4) utilizes empty space to support AP3's dishwasher operations and contains the Appliance Park's medical and fitness facilities. AP4 is also the Information Technology headquarters for GE Appliances & Lighting, housing a Platinum-LEED certified data center as of August 2011.[3]

Building 5 (AP5) assembles refrigerators with parts made in other Appliance Park locations. Until the 1980s, AP5 was the largest building in terms of employees, production, and production space.

Building 6 (AP6) contained air conditioner manufacturing operations until the division was sold in 1982. Since then, AP6 has been leased out to vendors and suppliers for GE and other companies. AP6 was also the new location for various GE electrical systems engineering teams that moved from that division's previous headquarters in Connecticut in 2005. It was destroyed by a 6-alarm fire on the morning of April 3, 2015.[4]

It might've been a "vendors and suppliers for GE and other companies" thing. Not definitive, unfortunately, but its ambiguity makes me wonder if whatever they made there was dangerous enough that no one knows what they make there, except for GE.