This week in Texas, estimates indicate that 161 people are still missing following the Hill Country floods, adding to the at least 120 deaths confirmed by authorities.

But that missing person tally might not be as precise as it seems.

Confusion and uncertainty often arise after a sudden disaster, making it challenging for local authorities to accurately assess how many reported missing individuals remain unaccounted for. In California’s 2018 Camp Fire wildfire, some on the missing list were later discovered to have been safe all along. The 2023 Maui fire’s death toll was 102, which was significantly lower than the initially feared 1,100 missing.

In Texas, officials in Kerr County received reports of several hundred people missing after the Fourth of July floods, according to Freeman Martin, the director of the Texas Department of Public Safety. By Tuesday, investigators reduced that number to 161, having identified instances of duplicate listings and individuals who were later found alive.

“There’s nothing to celebrate about how well we’ve done this far, but there’s a lot of work to be done,” Martin said.

Authorities announced a phone number and email address for people to report missing friends or family.

“We need to keep an accurate count, as accurate as possible,” Jonathan Lamb of the Kerrville Police Department said in a plea to the public Wednesday. “So if you’ve reported somebody missing and they’ve been recovered safely, please let us know.”

The flooding sent walls of water through Hill Country in the middle of the night, killing at least 27 campers and counselors at Camp Mystic, a century-old all-girls Christian summer camp along the Guadalupe River. More remain missing from that camp and elsewhere.

The search in 88-degree Fahrenheit heat (31 degrees Celsius) has been made harder by overturned cars, trees, mud and other debris left in the wake of the ferocious flood.

“We will not stop until every missing person is accounted for,” Gov. Greg Abbott said. “Know this also: There very likely could be more added to that list.”

In 2017, more than 20 people died in the Tubbs fire in northern California. Sgt. Juan Valencia of the Sonoma County Sheriff’s Office recalled that most of the 100 people initially reported missing to his agency were found safe.

Working through a list of names in a disaster is both meticulous and time-consuming work, he said.

“Put yourself in a family member’s shoes,” Valencia said. “They’re concerned about their loved one. Are they really the victim of a disaster or did they maybe lose their cellphone? Basically you start calling temporary shelters, check family, friends. You check social media. That’s how we were able to get a lot of those.”

And he acknowledged that searching for victims of a water disaster poses distinct challenges.

“Sometimes you find them miles away,” Valencia said.

The 2018 Camp Fire in California ended up killing nearly 100 people, though the Butte County Sheriff’s Office had a list of 1,300 people unaccounted for at one point.

Abbott said Texas authorities were trying to learn more about people who were not registered at a camp or a hotel for the holiday and left no paper or digital trail in the region. He had a firm message for anyone contacting police about a missing person.

“If you make a prank call or provide false information, that’s a crime. … So you better be correct,” the governor said.