Benton is a small town about 200 miles southwest of Louisville, and its high school serves students from all over Marshall County, which has a population of about 31,000.

John Parks, who owns the Fisherman’s Headquarters store about a mile from the school, described the area as a “very close-knit community” where just about everyone would have known a student at the school. “It’s personal when it’s a small town like this,” he said.

About a mile from the high school, a large American flag flew at half-staff over a Ponderosa Steakhouse on Tuesday night. Taylor McCuiston, 21, a manager at the restaurant who graduated from Marshall County High School two years ago, was working when the shooting occurred down the road.

“It was very scary because, like, 90 percent of the staff that works here goes to that school,” she said. “So for the first hour we were just scrambling trying to make sure they were all O.K. and accounted for.”

The town of Italy, Tex., is not any bigger than Benton. On Monday, a 15-year-old girl there was hospitalized after she was shot by a 16-year-old classmate, according to local news reports. That suspect, a boy, was taken into custody by the Ellis County Sheriff’s Department. The authorities said on Tuesday that the victim was recovering.

The F.B.I. study that Ms. Schweit helped write examined active shooter episodes in the United States between 2000 and 2013. It found that nearly one-quarter of them occurred in educational environments, and they were on the rise.

In the first half of the study period, federal officials counted 16 active shooter incidents in educational settings, meaning instances of a person “actively engaged in killing or attempting to kill people in a confined and populated area.” In the second half, the number rose to 23. (Many, but not all, of the school shootings tallied by advocates so far this year meet that definition.)