At least 27 campers and counselors at Camp Mystic perished in Friday's floods, with the total death toll in the floods now surpassing 100.

The data also highlights critical risks in other areas along the Guadalupe River in Kerr County, revealing more than twice as many Americans live in flood prone areas than FEMA's maps show.

Kerr County had discussed buying such things as water gauges and sirens after previous flood disasters. But as with many rural Texas counties, cost was an issue.

The risk of the catastrophic flooding that struck Texas Hill Country as people slept on July 4 and left at least 120 dead was potentially underestimated by federal authorities, according to an ABC News analysis of Federal Emergency Management Agency data, satellite imagery and risk modeling.

Many camps in the Guadalupe river region are adjacent or are partially inside high-risk flood zones, according to maps from the Federal Emergency Management Agency.

Kerr County repeatedly failed to secure a warning system, even as local officials remained aware of the risks and as billions of dollars were available for similar projects.

Catastrophic flooding struck central Texas on Friday as the Guadalupe River surged by more than 20 to 26 feet within 90 minutes, causing widespread devastation and forcing mass evacuations in Texas Hill Country. At least 80 people have been killed in the floods while others remain missing or displaced and more than 850 people required rescuing.

At least 27 campers and counselors were killed at Camp Mystic during the devastating Texas floods. Some are still missing.