Rescuers answered hundreds of desperate calls for help Sunday as floodwaters from the remnants of Hurricane Harvey climbed high enough to begin filling second-story homes, and authorities urged stranded families to seek refuge on their rooftops.

Areas south of Houston appeared to be at greatest risk. Some flooding was reported in downtown Houston and in the Texas Medical Center.

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.”

Officials urged people not to crawl into attics but to get on top of them.

Police evacuated two apartment complexes overnight in the Greenspoint neighborhood, rescuing more than 50 children from rising water.

“It breaks your heart,” Houston Police Chief Art Acevedo said as he stood in waist-high water during a livestream post on Twitter. “But it’s Texas. We’ll get through it.”

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.

In Friendswood near Houston, authorities asked people with flat-bottomed airboats or fuel for them to help rescue people from flooded homes, KPRC-TV in Houston reported Sunday morning.

Houston officials used dump trucks and city buses to move residents to higher ground.

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).

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.”

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. A trailer blocked much of one major intersection. Wood framing from ripped-apart houses was strewn along Route 35 on the town’s southern end.

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.

As many as 14 people suffered minor injuries, including slips and falls, scrapes and a broken leg, Mills said.

About 300,000 customers were without power statewide. Gov. Greg Abbott said it would probably be several days before electricity is restored.

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).

In Houston, authorities pleaded with people not to leave their homes as a flood emergency was declared.

“The streets are treacherous,” Houston Mayor Sylvester Turner said.

Elsewhere in the storm’s immediate aftermath, the Coast Guard had rescued 20 people from boats and barges in distress, said Capt. Tony Hahn, commander of the Corpus Christi sector.

The Corpus Christi port was closed with extensive damage. Because the city is the third-largest petrochemical port in the nation, the agency will be on the lookout for spills, Hahn said.

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 to a tropical storm by midday Saturday.

By 7 a.m. Sunday, Harvey 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.

The storm’s approach sent tens of thousands of people fleeing inland.

Just hours before landfall, the governor and Houston leaders issued conflicting statements on evacuation.

The governor urged more people to flee, but Houston officials recommended no widespread evacuations, citing greater danger in having people on roads that could flood and the fact that the hurricane was not taking direct aim at the city.

The last Category 4 storm to hit the U.S. was Hurricane Charley in August 2004 in Florida.

(AP)