The number of people reported missing in the wake of historic July 4 flooding in Kerr County, Texas, has dropped from a peak of more than 160 to three, with many now verified as being safe, officials said Saturday.

“Extensive follow-up work” and “extraordinary efforts” were credited with the reduction after 173 people statewide were reported missing amid floodwaters two stories deep, officials said in nearly identical statements from Kerr County and the city of Kerrville.

“This remarkable progress reflects countless hours of coordinated search and rescue operations, careful investigative work, and an unwavering commitment to bringing clarity and hope to families during an unimaginably difficult time,” Kerrville City Manager Dalton Rice said in the statements.

Dozens upon dozens of people reported missing by loved ones were taken off a list of missing persons after their safety was verified, officials said.

“Many individuals who were initially reported as missing have been verified as safe and removed from the list,” the city and county statements said. “This has been an ongoing effort as investigators worked diligently to verify reports of missing persons and confirm their status.”

County officials did not immediately respond to a request for more information Saturday. It wasn’t clear if any one factor, such as the return of cellphone service interrupted by the storm, may have been instrumental in locating those initially reported as missing.

Rapidly rising floodwaters in the early morning hours of July 4 swept through river-adjacent summer camp bungalows, washed cars off roadways and left some survivors clinging to trees.

A “flood wave” also swept down the Guadalupe River, rapidly increasing its depth and damaging structures along its banks. Federal weather data showed the Guadalupe, which runs through Kerville and Kerr County, rose 26 feet in 45 minutes.

At least 27 campers and staff members died at Camp Mystic, which was hosting more than 750 children when it was inundated by the sudden river flooding.

The process of warning residents is under scrutiny as the federal Integrated Public Alert & Warning System was not used to send Emergency Alert System texts to cellphone users in the region.

Sen. Ruben Gallego, D-Arizona, earlier this week called for a formal investigation into the Department of Homeland Security’s response to the flooding.

President Donald Trump toured flood-damaged Kerrville last week and defended the stance of his administration, saying the federal response was immediate. Homeland Security Secretary Kristi Noem was “there right from the beginning,” the president said.

State and local officials have also had to grapple with criticism of the lack of timely alerts being sent to residents ahead of the floods.

“It happened so rapidly that nobody, nobody could have anticipated it,” Kerrville City Manager Dalton Rice told NBC News this week, arguing that the historic and overwhelming nature of the flooding could barely be avoided with the best warnings and forecasts.