Houston : Massive flooding unleashed by deadly monster storm Harvey left Houston -- the fourth-largest city in the United States -- increasingly isolated Sunday as its airports and highways shut down and residents were rescued from their inundated homes by boat.
The city's two main airports suspended all commercial flights and two hospitals were forced to evacuate patients. A local television station also was knocked off the air.
At least three people have been killed so far, with reports of other fatalities still unconfirmed. As night fell, dramatic rescues -- sometimes by volunteers with their own boats -- were still taking place.
The National Hurricane Center called the flooding "unprecedented" and said the storm, which crashed ashore late Friday as a huge Category 4 hurricane, would move into the Gulf before doubling back midweek, bringing even more rain.
President Donald Trump, who had said he did not want to disrupt emergency efforts with a visit, is planning to head to the disaster zone on Tuesday, the White House announced.
Rising waters from Harvey inundated roads throughout the Houston area, affecting every major freeway and hamstringing efforts to move people to safety.
"It's crazy to see the roads you're driving on every day just completely under water," Houston resident John Travis told AFP.
Another city resident, Brit Dreger, said: "It doesn't look like we're going anywhere for a while."
Overwhelmed emergency services warned residents to head for high ground or climb onto rooftops -- not into attics -- so they could be seen by rescue helicopters. More than 2,000 rescues had been made so far.
The local ABC affiliate showed the helicopter rescue of a man and his six-year-son -- both named Jeremiah -- from the second floor of their home. Each only had the clothes on their back and a backpack.
"This is all we got," the father said. "We thank God. We thank God."
Emergency 911 operators in Houston received 56,000 calls in a 15-hour span -- seven times more than in a usual full day.
"We are going on fumes & our hearts ache for community we serve, but we will not stop!" said Houston police chief Art Acevedo.
Texas Governor Greg Abbott warned the operation was far from over, given the foreboding forecasts.
"The number of evacuees is increasing. The number in harm's way will increase also with the rain that is forecast to come," Abbott said, adding that the storm had already inflicted billions of dollars in damage.
Houston Mayor Sylvester Turner dismissed the idea that evacuations should have been ordered sooner.
"You issue an evacuation order and put everybody on the highway -- you really are asking for a major calamity," Turner told reporters.
Houston proper has a population of 2.3 million people, but the greater metropolitan area has more than six million.
