April 13 (Reuters) - More than 18,000 cows died after an explosion and fire at a family dairy farm in west Texas, marking the deadliest such barn blaze on record in the United States.

Firefighters rescued one employee from the South Fork Dairy near Dimmitt on Monday as flames raced through a building and into holding pens, according to images and statements from the Castro County Sheriff's Office.

The cause of the fire was under investigation and it was not immediately possible to contact members of the family who own the farm in one of Texas' biggest milk production counties.

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.