Over 100 people have died after heavy rain pounded Kerr County, Texas, early Friday, leading to "catastrophic" flooding, the sheriff said.

Experts say there was a number of factors that contributed to the tragedy including the extreme weather, the location of the holiday homes and timing. There was a large supply of moisture in the atmosphere from a tropical storm that had caused flooding in Mexico and then tracked north as it died out.

Here’s what to know about the deadly flooding, the colossal weather system that drove it in and around Kerr County, Texas, and ongoing efforts to identify victims.