More than 18,000 cows were killed after an explosion and fire at a family dairy farm in west Texas, making it the deadliest barn fire in US history.

According to photographs and statements from the Castro County Sheriff’s Office, firefighters rescued one employee from the South Fork Dairy in Dimmitt on Monday as flames raced through a building and into holding pens.

The cause of the fire was under investigation, and it was not possible to reach members of the family who own the farm in one of Texas’ most milk-producing counties right away.

The blaze prompted calls from the Animal Welfare Institute (AWI), among the oldest U.S. animal protection groups, for federal laws to prevent barn fires which kill hundreds of thousands of farm animals each year.

There are no federal regulations protecting animals from the fires and only a few states, Texas not among them, have adopted fire protection codes for such buildings, according to an AWI statement.

The blaze was the most devastating U.S. barn fire involving cattle since the AWI began tracking such incidents in 2013. Around 6.5 million farm animals have died in such fires in the last decade, most of them poultry.