A fire has destroyed a Jim Beam warehouse filled with 45,000 barrels of ageing bourbon, sending flames shooting into the night sky and generating so much heat that fire engine lights melted and the air filled with the smell of whiskey.

Forty firefighters from four counties responded to the blaze, which erupted in Versailles, Kentucky, late on Tuesday.

The orange glow from the inferno could be seen kilometres away, Woodford county emergency management director Drew Chandler said.

“It melted lights off some of the fire trucks, it got so hot,” Mr Chandler said.

He said firefighters who withstood the intense heat were able to keep the fire from spreading to some other nearby storage warehouses.

No injuries were reported.

Mr Chandler said the warehouse that burned, and a neighbouring one that was also damaged, were about the size of a football field – and up to seven storeys high.

Bloomberg estimates the lost barrels – about 1 per cent of Jim Beam’s entire stock – might be worth up to $425 million.

The smell of bourbon fills the air near the fire at a Jim Beam bourbon warehouse in Woodford County. pic.twitter.com/NMmsZt3feG

— Ryan C. Hermens (@ryanhermens) July 3, 2019

Mr Chandler said lightning might have been a factor in igniting the blaze, which started after thunderstorms in the area.

But investigators have not yet even been able to start looking for the cause and the fire, while contained, was being allowed to burn for several more hours on Wednesday.

“The longer it burns, the more of the distilled spirits burn with it,” he said.

“When they go to put it out, there will be less contaminated runoff that goes into a drinking-water tributary.”

Mr Chandler said fire suppression had started on Wednesday, and the site would soon be handed back to its owner.

“I anticipate local responders will clear the scene before dusk,” he said.

Company officials said they were working with authorities to assess environmental effects of the fire.

“We do know there has been runoff enter the creek,” said John Mura, a spokesman for the Kentucky Energy and Environment Cabinet.

“It has made its way into the Kentucky River.”

8+ hours later, the fire continues to burn at this Jim Beam property in Woodford County. Emergency Management officials tell me they expect it to last for several more hours. @LEX18News pic.twitter.com/RHqJrQ36xd

— Alex Valverde (@AlexValverdeTV) July 3, 2019

The runoff could have a “serious impact on aquatic life”, he said. Runoff is expected to create “low dissolved oxygen levels”, which could result in substantial fish kills, the agency said in a release.

Jim Beam is the world’s largest bourbon brand and is owned by Japan’s Beam Suntory.

“We are thankful that no one was injured in this incident, and we are grateful to the courageous firefighters from multiple jurisdictions who brought the fire under control and prevented it from spreading,” spokeswoman Emily York told CNN.

“Given the age of the lost whiskey, this fire will not impact the availability of Jim Beam for consumers.”

-with AAP