LOUISVILLE, Ky. (WDRB) - Investigators with Louisville Metro Arson estimate that to replace Building 6 at GE's Appliance Park could cost more than $400 million. 

Investigators say they still believe the the fire started in the southwest corner of the building, but with so much debris still left, firefighters are having a hard time reaching that specific spot. 

“The big problem we have right now is that on the top of the building was a large concrete vault,” said Major Henry Ott with Louisville Metro Arson. “It has collapsed down into the scene.”

Ott says that concrete slab is roughly the size of a large house, and at this point is sitting at a 90-degree angle. Firefighters are worried that it could fall. 

Over the next several days firefighters will begin the process of trying to remove that slab. Investigators hope that after that slab is removed, more light can be shed on how effective the sprinkler system inside the building was in combating the blaze.  

“I think that it activated," Ott said of the sprinkler system. "Now what it did after that, we're still working on that. We have alarms that show that it tripped and started, but we have to figure out what happened after that.”

Meanwhile, investigators say at this point they do not believe arson will be determined to be the cause of the fire, but it still can't be ruled out. 

“Usually you get an indication that there is an issue or a problem, and that's not been the case,” Ott said.

Most GE employees will return to work as normal on Monday. 

Investigators say it will likely be several weeks before a cause if officially determined.   

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