A fire has ripped through a massive Jim Beam warehouse in the United States, destroying about 45,000 barrels of ageing bourbon.

Key points: The blaze melted firetruck lights and caused bourbon to seep into a river

The blaze melted firetruck lights and caused bourbon to seep into a river The fire reportedly destroyed 1 per cent of Jim Beam's bourbon stocks, worth up to $425 million

The fire reportedly destroyed 1 per cent of Jim Beam's bourbon stocks, worth up to $425 million There would be no impact on Jim Beam supply but there are concerns for fish in a nearby river

The orange glow from the inferno in Kentucky — the traditional home of American bourbon — could be seen from kilometres away, according to local emergency services.

Woodford County emergency management director Drew Chandler said authorities were alerted to the fire shortly after 11:35pm on Tuesday (local time).

The blaze sent flames shooting into the night sky and generated so much heat that firetruck lights melted.

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

"It melted lights off some of the firetrucks, it got so hot," Mr Chandler said.

The alcohol-fuelled blaze was still burning at midday on Wednesday, but had been brought under control.

Bloomberg reported that the destroyed whiskey — which amounted to about 1 per cent of Jim Beam's bourbon inventory — could be worth up to $US300 million ($425 million).

"Given the age of the lost whiskey, this fire will not impact the availability of Jim Beam for consumers," the spirits company said in a statement.

Runoff liquor was seeping into the nearby Kentucky River, causing concern it would kill fish.

John Mura, a spokesman for the Kentucky Energy and Environment Cabinet said the runoff could have a "serious impact on aquatic life".

Runoff is expected to create "low dissolved oxygen levels," which could result in substantial fish kills.

The cause of the fire was not yet known.

ABC/wires