Water 'Swallowing Us Up': See Images From Houston

Harvey may be a tropical storm instead of a hurricane, but the devastation it is unleashing on Houston in the form of heavy rain and flooding is nonetheless severe. "Catastrophic and life-threatening flooding," says the National Weather Service of southeast Texas. "Worse than the worst-case scenario for Houston,” tweeted WeatherBell meteorologist Ryan Maue," per USA Today. Authorities were warning people to get to their roofs, and rescuers had to pick and choose which calls to go out on based on life-and-death severity, reports the AP.

Harris County Sheriff Ed Gonzalez used Twitter to field calls for assistance. Among those seeking help was a woman who posted: "I have 2 children with me and the water is swallowing us up." Houston Mayor Sylvester Turner said authorities had received more than 2,000 calls for help and would be opening the city's main convention center as a shelter. He urged drivers to stay off flooded roads to avoid adding to the number of stranded people. (More Hurricane Harvey stories.)