A Category 4 storm hit Texas on Friday and quickly began to flood communities all around Houston, the fourth biggest city in the US. In the days since the hurricane first came ashore, thousands of people have been rescued by volunteers, police, and the military. Many families got onto their roofs to wait to be rescued when the water filled their streets and homes. Rescuers have used boats, jet skis, helicopters, and human chains to save people and pets from the flood water. Many of the locations that had been set up as shelters have since flooded. Within less than a week, the storm could dump as much water as Houston normally gets in a full year.