An elderly South Texas couple died and their son was injured after a swarm of bees attacked them on their remote ranch, authorities said on Wednesday.

William Steele, 95, and his wife, Myrtle, 92, died and their son, Richard, 67, was injured after bees attacked them as they tried to clean a hunting cabin on their ranch near Hebbronville on Monday, an investigator with the Jim Hogg County Sheriff's Office said.

"It was a terrible thing," Investigator Reyes Espinoza told Reuters. "You don't prepare for something like that."

Richard Steele told investigators he and his parents were attacked after they moved a wood stove in the cabin and exposed a hive of bees, Espinoza said.

The son immediately drove about 15 miles to the nearest road, where he managed to call for help on a cell phone.

William Steele tried to escape the bees by running from the cabin, but he fell and succumbed to hundreds of bee stings, Espinoza said.

Myrtle Steele was airlifted to a Corpus Christi hospital, where she died on Tuesday. Her son was transported to a Laredo hospital and released, Espinoza said.

Espinoza said the bees swarmed deputies when they arrived at the scene on Monday.

"By the grace of God, we didn't get stung," he said. "You could literally scoop them off of us."

Espinoza said they were likely Africanized honey bees -- often called "killer bees" for their aggression -- which are common in south Texas.

The bees are hybrids from swarms originally introduced to Brazil from Africa, which absconded in the 1950s. They spread north through South and Central America, crossing into south Texas in 1990, according to the U.S. Department of Agriculture.

The bees swarm more frequently than native bees, and are extremely defensive. The USDA advises untrained individuals against trying to remove swarms. If attacked, individuals should run away quickly and not stop to help others.

Fatal attacks are rare, although the USDA gave no figures.