As authorities launch one of the largest search-and-rescue efforts in recent Texas history, they have come under intensifying scrutiny over preparations and why residents and youth summer camps that are dotted along the river were not alerted sooner or told to evacuate.

As questions swirl surrounding the timeline of who was notified about the flooding when, and if more could have been done, Department of Homeland Security Secretary Kristi Noem said an alert from the National Weather Service was sent to people in the flood zone -- but she said that doesn’t mean that people heard it.