Follow for live updates in the Texas flooding as the death toll rises to 120, as rescue operations start to shift to recovery phase

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

New satellite images released from Maxar Technologies show the destruction of the flash floods that have resulted in the deaths of more than 100 people over the July 4 weekend.Local authorities estimate around 160 people are still missing as Thursday marks the seventh day of the search for victims.

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.

In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.

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.

With more than 170 still missing, communities must reconcile how to pick up the pieces around a waterway that remains both a wellspring and a looming menace.