A United Cajun Navy commander leads flood recovery efforts in his hometown of Kerrville, Texas, where 121 people died in catastrophic flooding.

For the past five days, the United Cajun Navy has been working at a quarry, hoping to uncover flood victims buried beneath the rubble.

Nancy Epperson, right, and Brooklyn Pucek, 6, visit a memorial for flood victims along the Guadalupe River on July 10, in Kerrville, Texas. Here's what is still unknown about the hours before, during and after the deadly flash flood. The full extent of Texas officials' readiness is unclear.

As the Guadalupe River swelled from a wall of water heading downstream, sirens blared over the tiny river community of Comfort -- a last-ditch warning to get out for those who had missed cellphone alerts and firefighters going street-to-street telling people to get out.