When Jennifer Box began hearing reports of flash flooding in southeastern Missouri, where her two young sons were attending summer camp, she immediately thought back to the catastrophic floods that killed 25 campers in central Texas last July.

Ms. Box, who lives in St. Louis, dug up an email her sons’ camp had sent to parents after that disaster to reassure them that they had protocols in place were something similar to ever happen at Camp Taum Sauk in Reynolds County, which sits alongside the Black River.

On Friday morning, that plan unfolded as a foot of rain pounded the region in what the National Weather Service called a once-in-a-thousand-years rainfall event.

Around 2 a.m. on Friday, dozens of girls who were still half asleep were evacuated from their cabins in a low-lying area near the river and sent to sleep on the floor of the cafeteria.

As the river rose further and began to creep into the cafeteria, the girls moved to even higher ground on the tennis courts. They kept busy by making bracelets, playing board games and doing other arts and crafts. The boys, whose cabins were on higher ground, remained inside, chatting and listening to the radio. Parents, meanwhile, shared any information they could gather with one another through group messages.

“It was very harrowing,” said Ms. Box, who received an email Friday morning from the camp directors saying that the children had been moved to a higher location as a precautionary measure. “We knew they were safe, but we didn’t know how to get to them, and that’s kind of your worst nightmare.”

Over the next 12 hours, Gov. Mike Kehoe of Missouri declared a state of emergency and activated the National Guard to support rescues. In the afternoon, Black Hawk helicopters airlifted about 200 campers and counselors out of Camp Taum Sauk to a nearby elementary school where parents picked up their children.

For the campers, it all seemed like an adventure.

“When I first heard we were getting on helicopters, I was kind of scared,” said Everett Box, 11, who was attending Camp Taum Sauk for the third summer. “Then I kind of warmed up to it and was superexcited to go on it.”

The evacuation seemed well-organized and more controlled than the frantic response at Camp Mystic in central Texas last year, where a lack of adequate emergency plans left the camp overwhelmed and unprepared to get scores of girls to safety, according to findings from state investigators. That investigation also concluded that efforts to reunite families were chaotic, and at least 39 adults who were nearby and could have assisted were given no instructions to do so by camp leadership.

Ultimately, the flood on July 5, 2025, killed 25 campers, two counselors and the camp’s executive director. The company operating the camp filed for bankruptcy last month, and parents of campers and counselors who died have filed lawsuits against Camp Mystic and members of the Eastland family, who directed it.

In Missouri, the heavy rain started Thursday night as clusters of thunderstorms developed and moved over the same area again and again in southeastern Missouri. This phenomenon is known as “training,” as the storms move “much like a train moves over a track,” said Matt Beitscher, a meteorologist with the Weather Service office in St. Charles, Mo. A similar weather pattern set up over Kerr County, Texas, in July 2025.

Just before midnight up to three inches of rain had fallen and more was coming. The Weather Service issued a flash flood warning for Reynolds County and central Iron County.

The downpours continued into Friday morning, with locations across southwestern Missouri recording six to over 12 inches of rain and the warnings staying in place and expanding into nearby counties. Reynolds County and the area around the camp is within the area that was estimated to have received around a foot of rain.

“That was probably where the worst of it was,” Mr. Beitscher said.

In nearby Crawford County, one missing person, a woman named Faith Gregory, was found dead about two miles downstream from her residence, the county sheriff’s office said Saturday.

Just after 4 a.m. on Friday, the Weather Service issued its highest level flood alert, a flash flood emergency, stating that life-threatening flooding was occurring.

“This is a particularly dangerous situation,” the warning said. “Seek higher ground now!”

On Saturday, a flood watch remained in effect across much of southeast Missouri and spread east into Kentucky and Tennessee and parts of the surrounding states.

A camper named Cate Hensley, 11, remembered looking out toward the river from her cabin on Thursday, unable to see the water. By Friday, she said, it was difficult to tell where the river ended and the road began. Cate said her cabin was covered in broken glass and she was unable to return to collect her belongings.

Even after hearing about the floods at Camp Mystic, Cate’s mother, Melissa Hensley, said she never rethought sending her daughters to Camp Taum Sauk.

“This is their happy place,” she said. “They plan for this every single year.”

Georgia Gee contributed research.