Smoke rises at the Southfork Dairy Farms, after an explosion and a fire killed around 18,000 cows, near Dimmitt, Texas. Reuters

A "horrific" explosion and fire at a dairy farm in the southern US state of Texas killed about 18,000 head of cattle and injured one agricultural worker, authorities said on Thursday.

"This was the deadliest barn fire for cattle in Texas history and the investigation and cleanup may take some time," Texas Agriculture Commissioner Sid Miller said in a statement.

The explosion and fire ripped through the Southfork Dairy Farms near the town of Dimmitt in the Texas Panhandle on Monday night.

Firefighters and police rushed to the scene and "determined that one person was trapped inside," the Castro County Sheriff's Office said on Facebook. The person was rescued and flown to a hospital in Lubbock, it said.

The cause of the explosion and fire were not immediately clear, said Miller, who described it as a "horrific event."

Smoke rises at the Southfork Dairy Farms, after an explosion near Dimmitt, Texas. Reuters

"Once we know the cause and the facts surrounding this tragedy, we will make sure the public is fully informed — so tragedies like this can be avoided in the future," he said.

Castro County Sheriff Sal Rivera told the CBS affiliate in Amarillo that a system to remove manure from the barns may have gotten "overheated."

He said methane may have "ignited and then spread out with the explosion and the fire," adding that a probe would have to determine the precise cause.

"Farms must do more to protect animals by adopting commonsense fire safety measures," tweeted the Animal Welfare Institute, one of the oldest animal welfare charities in the United States, referring to the Texas tragedy.

"This would be the most deadly fire involving cattle in the past decade, since we started tracking that in 2013,” institute spokesperson Marjorie Fishman said on Thursday.

The institute also tracks barn fires that kill other livestock, including poultry, pigs, goats and sheep.

"The deadliest barn fire overall since we began tracking in 2013... was a fire... at Hi-Grade Egg Producers North, Manchester, Indiana, which killed 1 million chickens,” according to Fishman.

A 2022 report by the institute noted "several instances in which 100,000 to 400,000 chickens were killed in a single fire.”

A phone call to Southfork Dairy rang unanswered on Thursday.

A spokesperson for the state insurance department, which oversees the fire marshals’ office, said only that the fire is under investigation and referred questions to Rivera, who did not immediately return phone calls for comment on Thursday.

Insurance department spokesperson Gardner Selby declined comment on the injured person's condition.

Dimmitt is about 80 kilometres southwest of Amarillo and about 547 kilometres northwest of Dalllas.

Agencies