As rescue teams continue their search for flood victims, a flash flood watch has been issued in the Texas Hill Country, making an already difficult task that much harder.

Additional dangerous flash flooding incidents are likely in the coming days as high humidity, daytime heat and storm systems interact from the Atlantic Seaboard to the Plains, Gulf coast and Southwest.

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

A large percentage of people still unaccounted for were probably visiting the area, Kerr County Judge Rob Kelly said.

The National Weather Service urged people to avoid travel if a flash flood warning was in place for their area.

State and local officials said they did their best to coordinate evacuations and rescues, but better cellphone service might help in future floods.

Eight-year-old girls at sleep-away camp, families crammed into recreational vehicles, local residents traveling to or from work. These are some of the victims.

Flash floods are occurring across the U.S., from Texas to New Jersey. Here's what you should know as risks escalate.