Mr. Trump said his administration was working with state and local officials and that Department of Homeland Security Secretary Kristi Noem would be arriving in Texas shortly. DHS oversees the Federal Emergency Management Agency.

As the deadly floodwaters in parts of central Texas recede, there are growing questions about how the catastrophic rainfall seemingly caught the area by surprise. Some local officials say the National Weather Service underestimated the extreme rain but the agency says an initial flood watch was issued Thursday afternoon.