Was GE Appliance Park Fire Caused by Lightning?

UPDATE 4/9/15: Even now, a week later, the cause has not been discovered, but the media is still quoting lightning as a possible cause.

A massive fire broke out after an explosion at the GE's Appliance Park in Louisville, Kentucky April 3, 2015. Was it weather-related?

As the fire broke out, the city was suffering under severe thunderstorms with massive amounts of lightning and flooding rain. Just looking at these maps, I surmised that either could be to blame (lightning strike map below, and rainfall map also available).

Before the day was out, a local TV station was saying "an early investigation is leaning toward a lightning strike as the cause of the blaze." I decided to look at lightning strike data to find out if a strike was recorded on the building or grounds. (I've demonstrated in the past that their accuracy is as good as they claim). The following map was delivered by Vaisala, who also provides the lightning map shown above.

In my opinion, this means lightning did not hit the area. The closest ground strike (G) was about three miles away, too far to cause damage at the site, unless there was some sort of unusual power surge.

The smoke from the fire was incredible, and even showed up on radar, going up to around 7,000 feet in the air.

Here's what it looked like from afar: