There are millions of wild hogs in Texas, though they are rarely violent toward humans. Texans mostly encounter them when the animals have uprooted a flower bed or damaged crops. Unlike domesticated pigs, feral hogs can become aggressive if they feel trapped, or if a female hog is defending her offspring. Most weigh about 200 pounds, though they can grow to more than 500.

“Feral pigs will lunge at you and attack you” if they perceive a threat, said John J. McGlone, a professor of animal behavior at Texas Tech University who has studied feral and domestic hogs.

There were about 100 documented attacks by feral hogs on humans in the United States between 1825 and 2012, four of which were fatal, according to a 2013 study. The most recent of those was also in Texas, in 1996.

Three of the four fatal attacks were by pigs wounded by hunters. But feral hog attacks in urban and suburban areas have increased since the mid-1990s, said John J. Mayer, the study’s author. He warned that many attacks likely go unreported, especially in rural regions.

Sheriff Hawthorne said the tragedy was one of the worst he had seen in his 35-year career. He said that as developers build houses in rural areas, more wild hogs are coming into contact with people. But the only other hog attack he had worked on was when one had attacked a pet cat.

“Feral hogs are just that: They’re feral, they’re wild and they roam,” he said. “One minute they’re tearing up the land on one ranch, the next minute they’re tearing up the ranch in the town over.”

Feral hogs descended from European wild boars, which were first brought to Texas in the 1500s and sometimes bred with domesticated pigs, Professor McGlone said. They mostly eat vegetation but are omnivorous, and can briefly run at speeds up to 30 m.p.h.