Texas officials are looking for an unknown number of missing residents, including at least 11 girls from a private Christian camp, after a rapid, massive flood overwhelmed Kerr and Bandera counties where the Guadalupe River rose 26 feet in under two hours.

With at least 70 dead and more than 850 rescued or recovered, hopes are dwindling more than 48 hours after campers were washed away from Camp Mystic and hundreds more escaped a flash flood that came hurtling through the Texas Hill Country, delivering an estimated 1.8 trillion gallons of rain.

Authorities on Saturday recovered three bodies of individuals tied to the camp — Camp Mystic’s director Dick Eastland, who had been trying to save the campers, a nearby camp director, Jane Ragsdale, and camper Sarah Marsh.

“Our family is completely devastated by the loss of Sarah and her dear friends at Camp Mystic. This is a tragedy that no parent can prepare for, it will never be right this side of Heaven,” the family of Ms. Marsh wrote in a statement.

More rain and potential scattered thunderstorms are expected Sunday afternoon and evening in the area known as Flash Flood Alley, where the river’s water rose more than one foot every five minutes between 3:00 a.m. and 4:30 a.m. on Friday morning.

But even in this area where flooding is common, the Independence Day deluge caught the community by surprise, and raised questions about budget cuts to the nation’s emergency weather service. Local officials are also being questioned about their preparedness despite the National Weather Service for the Austin/San Antonio area issuing a flood watch 12 hours before the thunderstorms and activating emergency warnings for “life-threatening flooding” three hours before the catastrophic weather event that occurred in the middle of the night. 

“We have all wanted more time and more warning and more alerts and more notification” before storms hit, Homeland Security Kristi Noem said Saturday. Noting the unpredictability of weather, Ms. Noem said that the dams held and Coast Guard swimmers had saved hundreds. FEMA and other federal resources had been called into service immediately. 

On Sunday President Trump signed a federal disaster declaration for Kerr County “to ensure that our Brave First Responders immediately have the resources they need.”

“These families are enduring an unimaginable tragedy, with many lives lost, and many still missing,” Mr. Trump said in a statement on Truth Social.

Ms. Noem said that federal first responders are working with state and local authorities “to ensure the people of Texas get the support they need as search efforts continue and recovery begins.”

More than 1,800 remain without power in Kerrville, the center of the disaster where officials are going through debris that included entire homes lifted from their foundations and dragged down the river. Twenty-one counties have been included in the state’s disaster declaration.

The governor of Texas, Greg Abbott, declared Sunday a day of prayer as local churches and other community services organized food drives and intake shelters to assist displaced families.

Texas’ Emergency Management Chief Nim Kidd said Saturday that more than 1,300 state personnel from 15 state agencies, including the departments of Public Safety, Forest Service, Parks and Wildlife, and Urban Search and Rescue are working with local responders as well as health and medical specialists. Searchers are using boats, helicopters, and drones to look for victims who may be stranded in trees or on high ground where roads are washed out below.

Separately, an ad hoc volunteer group from Louisiana formed after Hurricane Katrina, the United Cajun Navy, is offering its search and rescue services while the Houston Texans football team said it is offering $500,000 to provide support for rescue, recovery, and resources for the Hill Country communities.