A police official said there was no one inside when the roof caved in.
Kentucky distilleries are aging a total of 6.8 million bourbon barrels, according to the Kentucky Distillers' Association.
A spokeswoman for Barton 1792, Amy Preske, said the collapse happened in Warehouse #30.
Nelson County Emergency Management spokesman Milt Spalding said about 9,000 barrels of aging bourbon were affected.
"We are assessing how numerous impacted barrels can be recovered", said Amy Preske, a spokeswoman for Sazerac, a Louisiana-based spirits company.
Pardon bourbon lovers for crying in their beer after half of the barrels being aged at a Kentucky distillery building fell to the ground when part of the structure collapsed. At this time we do not know which Barton 1792 brands or customers will be impacted.
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The Warehouse incident will not affect normal operations or tourism activities; the Distillery expects to be open for tours on Saturday and it will resume normal business operations on Monday.
Officials are working to determine if any of the liquor spilled out. Representatives from the state's Department for Environmental Protection were dispatched to the scene.
Spalding says there were no injuries inside the structure, which was holding about 18,000 barrels.
"We've had some warehouse fires, but I can't recall having a collapse", he said.
Barton is owned by the Sazerac Company which also owns Buffalo Trace in Frankfort, Ky.
The Barton distillery, established in 1879, includes 29 storage warehouses and 22 other buildings, according to its website. It's located about 40 miles from Louisville, Kentucky.