FRANKFORT, Ky. (AP) — A fire destroyed a massive Jim Beam warehouse filled with about 45,000 barrels of bourbon, sending flames shooting into the night sky and generating so much heat that firetruck lights melted, authorities said Wednesday.

Firefighters from four counties responded to the blaze that erupted late Tuesday. Lightning might have been a factor, but fire investigators haven't been able to start looking for the cause, Woodford County Emergency Management Director Drew Chandler said.

No injuries were reported, Chandler said. The fire was contained but was being allowed to burn for several more hours Wednesday, he said.

"The longer it burns, the more of the distilled spirits burn with it," he said in a phone interview. "So when they go to put it out, there will be less contaminated runoff that goes into a drinking-water tributary."

Company officials said they are working with authorities to assess environmental effects.

The distiller hired an emergency cleanup crew and state environmental officials were coordinating efforts to control bourbon runoff into a nearby creek that flows into the Kentucky River, said John Mura, a spokesman for the Kentucky Energy and Environment Cabinet.

"We do know there has been runoff enter the creek," Mura said. "And it has made its way into the Kentucky River."

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.

State officials warned recreational users on the Kentucky River that runoff will result in water discoloration, foaming and an odor.

The distilling company said the multi-story warehouse that burned contained "relatively young whiskey," meaning it had not reached maturity for bottling for consumers. Bourbon acquires its color and flavor while aging for years in charred new oak barrels.

"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.

The distiller said it was grateful to the "courageous firefighters" who brought the blaze under control and kept it from spreading. A second warehouse sustained minor exterior damage but its contents remained intact, the company said.

The whiskey maker suffered a total loss in the burned warehouse. The destroyed whiskey amounted to about 1% of Beam's bourbon inventory, it said.

One standard bourbon barrel usually holds about 53 gallons of bourbon that eventually turns into around 150 to 200 750 milliliter bottles, the Courier Journal reported. If all the barrels held bourbon, that would be a loss of at least 6 million bottles, the Louisville newspaper reported.

Jim Beam is the world's largest bourbon brand. The classic American whiskey brand is owned by Suntory Holdings Ltd., a Japanese beverage company.

Authorities were alerted of the fire shortly after 11:35 p.m. EDT Tuesday, Chandler said. The orange glow from the inferno could be seen miles away, he said.

Firefighters who withstood the intense heat were able to keep the fire from spreading to some other nearby storage warehouses, he said.

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

The destroyed warehouse, near the Woodford-Franklin county line, was about 100 yards (91 meters) from Glenns Creek, a tributary of the Kentucky River, he said. Existing containment berms were reinforced with sand to try to prevent runoff into the creek, he said.

Beam Suntory officials said the distiller has a "comprehensive" warehouse safety program that includes regular inspections and "rigorous protocols" to promote safety. The distiller said it operates 126 barrel warehouses in Kentucky that hold about 3.3 million barrels for its brands.

The Beam fire was the latest warehouse loss suffered by a Kentucky distiller.

Last month, a storm caused the partial collapse of a warehouse at O.Z. Tyler Distillery in Owensboro. The painstaking process of recovering barrels is continuing as part of the distiller's overall plan that included taking down the entire structure.

Another Kentucky bourbon barrel warehouse collapsed last year. Half of a warehouse collapsed at the Barton 1792 Distillery in Bardstown in June 2018, and the other half came down two weeks later.

Kentucky distillers produce 95% of the world's bourbon, according to the Kentucky Distillers' Association. The state's bourbon sector is in the midst of a $2.3 billion-plus building boom among KDA members — signaling distillers' confidence that growing demand for their spirits will continue. Projects include new and expanded production facilities, more warehousing and bottling lines and new and expanded tourism centers.