HOUSTON -- Rescuers answered thousands of desperate calls for help Sunday as floodwaters from the remnants of Hurricane Harvey rose high enough to begin filling second-story homes, and authorities urged stranded families to seek refuge on rooftops.
A fleet of helicopters, airboats and high-water vehicles confronted flooding so widespread that authorities had trouble pinpointing the worst areas. Rescuers got too many calls to respond to each one and had to prioritize life-and-death situations.
Harris County Sheriff Ed Gonzalez used Twitter to field calls for assistance for those trapped inside homes, attics and vehicles. Among those seeking help was a woman who posted: "I have 2 children with me and the water is swallowing us up."
People used inflatable beach toys, rubber rafts and even air mattresses to get through the rising waters to higher ground. Others simply waded while carrying plastic trash bags stuffed with their belongings.
Officials urged people not to crawl into attics but to get on top of them. The Coast Guard suggested they wave sheets or towels to draw attention to themselves.
"It's catastrophic, unprecedented, epic -- whatever adjective you want to use," said Patrick Blood, a NWS meteorologist, told the Houston Chronicle. "It's pretty horrible right now ... I know for a fact this is the worst flood Houston has ever experienced ... Worse than (Tropical Storm) Allison. It's so widespread."
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Houston Mayor Sylvester Turner said authorities had received more than 2,000 calls for help and would be opening the city's main convention center as a shelter. He urged drivers to stay off flooded roads to avoid adding to the number of stranded people.
"I don't need to tell anyone this is a very, very serious and unprecedented storm," Turner told a news conference. "We have several hundred structural flooding reports. We expect that number to rise pretty dramatically."
Police evacuated two apartment complexes overnight in the Greenspoint neighborhood, rescuing more than 50 children from rising water. Houston Police Chief Art Acevedo stood in waist-high water during a livestream post on Twitter.
Rainfall of more than 4 inches per hour resulted in water levels higher than in any recent floods and higher than during Tropical Storm Allison in June 2001, said Jeff Linder of flood control district in Harris County, which includes Houston.
Emergency teams came by land, water and air.
In Friendswood near Houston, authorities asked people with flat-bottomed airboats or fuel for them to help rescue people, KPRC-TV in Houston reported Sunday morning.
In Houston, dump trucks and city buses were used to ferry residents to higher ground.
The Coast Guard, which received more than 300 requests for help, deployed five helicopters and asked for additional aircraft from New Orleans.
Staff at a Houston television station broadcasting live coverage of the floods had to evacuate after water from the nearby Buffalo Bayou started to gush into the building.
KHOU-TV tweeted images Sunday of water pushing through a front door and flooding the lobby. The anchors and news operations then moved to a second floor before finally abandoning the station.
The director of the Federal Emergency Management Agency, Brock Long, said the government expected to conduct a "mass care mission" and predicted that the aftermath of the storm would require FEMA's involvement for years.
"This disaster's going to be a landmark event."
President Donald Trump tweeted Sunday morning that he would visit Texas.
"I will be going to Texas as soon as that trip can be made without causing disruption," the president posted on Twitter. "The focus must be life and safety."
The rescues unfolded a day after the hurricane settled over the Texas coastline. It was blamed for killing at least two people and injuring up to 14.
Anxiety ran high throughout the region between Corpus Christi and Houston because some of the areas with the greatest hurricane damage were inaccessible to rescuers. And the forecast for days of steady rain threatened to inundate the region's flat landscape with as much as 40 inches (100 centimeters).
In the island community of Port Aransas, population 3,800, officials were unable to fully survey the town because of "massive" damage. Police and heavy equipment had only made it into the northernmost street.
"I can tell you I have a very bad feeling and that's about it," said Mayor Charles Bujan, who had called for a mandatory evacuation but did not know how many heeded the order.
Some of the worst damage appeared to be in Rockport, a coastal city of about 10,000 that was directly in the storm's path. The mayor said his community took a blow "right on the nose" that left "widespread devastation," including homes, businesses and schools that were heavily damaged. Some structures were destroyed.
Rockport's roads were a mess of toppled power poles and other debris. Harvey's relentless wind tore the metal sides off the high school gym and twisted the steel door frame of its auditorium.
"We're still in the very infancy stage of getting this recovery started," said Aransas County spokesman Larry Sinclair.
One person was killed in Aransas County when in a fire at home during the storm, county Judge C.H. "Burt" Mills Jr. said.
Another person — a woman who tried to get out of her vehicle in high water — died in flooding in Harris County, where Houston is located, , though authorities had not confirmed a cause of death, said Gary Norman, a spokesman for the Houston emergency operations center.
Meanwhile, the storm was barely moving. Rainfall totals varied across the region, with Galveston receiving around 8 inches (20 centimeters), Houston 11 (28 centimeters) and Aransas 10 (25 centimeters). Tiny Austwell got 15 inches (38 centimeters).
The fiercest hurricane to hit the U.S. in more than a decade came ashore late Friday about 30 miles (48 kilometers) northeast of Corpus Christi as a mammoth Category 4 storm with 130 mph (209 kph) winds.
Harvey weakened Saturday to a tropical storm. By Sunday morning the system was centered about 65 miles southeast of San Antonio, with maximum sustained winds of about 45 mph (72.42 kph), according to the National Hurricane Center, which described the flooding as "catastrophic."
Harvey came ashore as the fiercest hurricane to hit the U.S. in 13 years and the strongest to strike Texas since 1961's Hurricane Carla, the most powerful Texas hurricane on record.
Associated Press writers Juan Lozano and Nomaan Merchant in Houston; Tammy Webber in Chicago; David Phillip in Dickinson, Texas; and Jamie Stengle, David Warren and Claudia Lauer and in Dallas contributed to this report.