Hurricane Harvey has caused bad wreckage after hitting landfall in Texas on Friday night.
High winds kept emergency crews out of many places, and authorities said it could be hours before emergency teams are able to fully assess the damage.
So far, there have been 338,000 power outages across the state, he added.
President Trump on Friday night approved a disaster declaration for the state, freeing up federal resources to assist victims.
A CNN report Saturday said large portions of southeast Texas "were littered with uprooted trees, toppled signs, flagpoles that snapped like toothpicks and clusters of bricks peeled like scabs from walls and rooftops".
The storm is expected to drop 15 to 30 inches of rain with isolated maximum amounts of 40 inches over the middle and upper Texas coast through next Wednesday.
Some areas are already seeing flooding, with the National Hurricane Centre warning people against driving into standing water.
"We've already taken a severe blow from the storm, but we're anticipating another one when the flooding comes", Rockport mayor Charles Wax told CNN.
Rockport resident Robert Jackson said riding out the storm was "about the most stressful thing I've ever been through".
By 5 a.m. Saturday morning, weather officials downgraded the storm to a Category 1 hurricane as it continued to make its way inland. This will most likely result in significant flooding. The Houston, Texas City and Baytown region is home to 11 refineries that in total represent 14 percent of processing capacity in the U.S.
That bleak tip underscored the stakes in Rockport late Friday, when Harvey slammed the city, unleashing a torrent of heavy rain and strong winds. According to the U.S. Bureau of Safety and Environmental Enforcement, almost 10 percent of oil production and 15 percent of natural gas output in the Gulf has been shut down.
Search and rescue operations are continuing along the Texas Gulf Coast.
"The impact on the energy industry could potentially be devastating" for the next week, John LaRue, executive director of the Port of Corpus Christi, told CNNMoney.