Over just two hours, the Guadalupe River at Comfort, Texas, rose from hip-height to three stories tall, sending water weighing as much as the Empire State building downstream roughly every minute it remained at its crest. The force of floodwater is often more powerful and surprising than people imagine.

Sisters Blair Harber, 13, and Brooke Harber, 11, were killed, along with their grandparents, when surging floodwaters ripped through the community. Their parents were staying in a different home at Casa Bonita and survived, according to the family's GoFundMe.

On Wednesday, hundreds prayed, wept, and held one another at a prayer service, among the first of many somber gatherings to come in the weeks ahead.

Officials in Kerr County, the hardest-hit region, said the number of missing remained unchanged since Tuesday, at 161. The floods have killed at least 120 people statewide.

At least 161 people remain missing in Kerr County, Texas, as authorities and volunteers search the Guadalupe River for victims.