Flash floods in Texas killed at least 100 people over the Fourth of July holiday weekend and left others still missing, including girls attending a summer camp. The devastation along the Guadalupe River, outside of San Antonio, has drawn a massive search effort as officials face questions over their preparedness and the speed of their initial actions.

Here's what to know about the deadly flooding, the colossal weather system that drove it in and around Kerr County, Texas, and ongoing efforts to identify victims.

Massive rain hit at just the wrong time, in a flood-prone place

The floods grew to their worst at the midpoint of a long holiday weekend when many people were asleep.

The Texas Hill Country in the central part of the state is naturally prone to flash flooding due to the dry dirt-packed areas where the soil lets rain skid along the surface of the landscape instead of soaking it up. Friday's flash floods started with a particularly bad storm that dropped most of its 12 inches (30 centimeters) of rain in the dark early morning hours.

After a flood watch notice midday Thursday, the National Weather Service office issued an urgent warning around 4 a.m. that raised the potential of catastrophic damage and a severe threat to human life. By at least 5:20 a.m., some in the Kerrville City area say water levels were getting alarmingly high. The massive rain flowing down hills sent rushing water into the Guadalupe River, causing it to rise 26 feet (8 meters) in just 45 minutes.

Death toll is expected to rise and the number of missing is uncertain

In Kerr County, home to youth camps in the Texas Hill Country, searchers have found the bodies of 75 people, including 27 children, Sheriff Larry Leitha said Monday morning. Fatalities in nearby counties brought the total number of deaths to 94 as of Monday afternoon.

Ten girls and a counselor were still unaccounted for at Camp Mystic, a Christian summer camp along the river.

For past campers, the tragedy turned happy memories into grief.

Beyond the Camp Mystic campers unaccounted for, the number of missing from other nearby campgrounds and across the region had not been released.

Gov. Greg Abbott on Sunday had said that there were 41 people confirmed to be unaccounted for across the state and more could be missing.

Kerrville City Manager Dalton Rice said during a Monday news conference he couldn't give an estimate of the number of people still missing, only saying “it is a lot.”

Officials face scrutiny over flash flood warnings

Survivors have described the floods as a “pitch black wall of death” and said they received no emergency warnings.

Kerr County Judge Rob Kelly, who lives along the Guadalupe River, said Saturday that “nobody saw this coming.” Officials have referred to it as a “100-year-flood,” meaning that the water levels were highly unlikely based on the historical record.

And records behind those statistics don’t always account for human-caused climate change. Though it’s hard to connect specific storms to a warming planet so soon after they occur, meteorologists say that a warmer atmosphere can hold more moisture and allow severe storms to dump even more rain.

Additionally, officials have come under scrutiny about why residents and youth summer camps along the river were not alerted sooner than 4 a.m. or told to evacuate.

Rice said Monday that he did not immediately know if there had been any communication between law enforcement and the summer camps between 1 a.m. and 4 a.m. on Friday. But Rice said various factors, including spotty cell service in some of the more isolated areas of Kerr County and cell towers that might have gone out of service during the weather, could have hindered communication.

Rice said officials want to finish the search and rescue and then review possible issues with cell towers, radios and emergency alerts.

Officials noted that the public can grow weary from too many flooding alerts or forecasts that turn out to be minor.

Kerr county officials said they had presented a proposal for a more robust flood warning system, similar to a tornado warning system, but that members of the public reeled at the cost.

Monumental clearing and rebuilding effort

The flash floods have erased campgrounds and torn homes from their foundations.

"It’s going to be a long time before we’re ever able to clean it up, much less rebuild it," Kelly said Saturday after surveying the destruction from a helicopter.

Other massive flooding events have driven residents and business owners to give up, including in areas struck last year by Hurricane Helene.

President Donald Trump said he would likely visit the flood zone on Friday.

AP photographers have captured the scale of the destruction, and one of Texas' largest rescue and recovery efforts.