Hurricane Harvey has killed a second person in Texas as the strongest hurricane to hit the US in 13 years continued to bring torrential rain, and with it the risk of catastrophic flooding to Houston, the nation’s fourth-largest city.

The second fatality was a woman who died after she drove into flooded streets on Houston’s west side late on Saturday. It appeared she got out of her vehicle in high waters and her body was found a short distance away by neighbours, said emergency authorities.

More than 2300,000 customers across Texas were still without electricity as Harvey threatened to stall, setting up for several days of rainfall that could tally 50in (127cm), more than 4ft (1.2m), by Wednesday in some spots. Texas governor Greg Abbott said about 20in (50.8cm) of rain had fallen in the Corpus Christi area and 16in (40.6cm) in the Houston region.

“There is the potential for very dramatic flooding,” he said in an afternoon media conference in Austin. “Our biggest concern is the possibility of between 20 and 30 more inches of rain in areas ranging from Corpus Christi over to Houston.”

Abbott expanded his declaration of a state of disaster by 20 counties, to 50. Numbers of injuries and fatalities were not yet clear, he said.

In the small seaside town of Rockport, which was directly in Harvey’s path when it came ashore and was particularly badly hit. One person was killed in a house fire, the mayor said. The Coast Guard reported that helicopters rescued 18 people from boats and barges in distress.

Dozens of Houston-area roads were reported flooded. As of midday, 704 flight cancellations had been announced at George Bush Intercontinental airport and 123 at Hobby, though a break in bad weather allowed departures to resume at Bush.

Brock Long, administrator of the Federal Emergency Management Agency (Fema), said on Twitter that the storm was transitioning into a “deadly inland event”.

In a Saturday morning update, the National Hurricane Center (NHC) said that though winds had slowed to a maximum 80mph, Harvey was “moving slowly over Texas producing torrential rains … catastrophic flooding expected over the next few days”.

Houston, about 200 miles north-east of where Harvey made landfall, began seeing wind and rain on Friday. It is notoriously flood-prone and more than 6.5m people live in the metropolitan area. Though officials decided against ordering a mass evacuation from central Houston, voluntary and mandatory evacuations were issued on Saturday for parts to the south west, near two rivers in Fort Bend County.

Levels in Houston’s bayous were increasing, giving rise to the prospect that they will burst their banks if the rain continues as predicted.

“This is just day one,” Houston mayor Sylvester Turner told Good Morning America. “We anticipate a lot of rain over the next four or five days.”

Traffic was light in the city and many stores were closed, though an exception was a doughnut shop in the suburb of Katy, where Don Mach and his Keeshond dog, Bo, were having breakfast.

Mach said he was “very concerned” about Harvey. “We got 5.5in of rain last night. That came down probably in about four hours,” the 70-year-old said. “That water can only go so many places.”

Oil companies began shutting down operations in and along the Gulf in anticipation of the storm, and gas prices rose. There was anxiety that Harvey could provoke flooding to hit the region’s vast refining and petrochemical facilities and unleash toxic discharges into adjacent communities or Galveston Bay.

Juan Parras, an environmental campaigner in east Houston, said he was worried severe flooding or a storm surge could cause leaks or dislodge chemical tanks.

“When they move off their concrete base all that oil, whatever’s in those tanks, just goes out into the community and we have a lot of tanks here,” he said. “We have almost a 52-mile stretch of nothing but refineries and oil tanks.”

Neighbourhoods closest to the plants are some of the least-affluent and most-polluted in the region. “The worst off will be hit the hardest,” Parras said.

Harvey made landfall near Corpus Christi late on Friday as a category 4 hurricane with maximum winds of 130mph. It was the first category 4 storm in the US since 2004 when Charley menaced Florida; Texas had not endured such a powerful hurricane since Carla in 1961.

Harvey was downgraded to a tropical storm after battering Rockport and another seaside town, Port Aransas. Reports indicated severe damage to infrastructure and buildings including a high school, a hotel and a senior living complex where a roof collapsed.

Rockport’s mayor pro tem had urged locals to evacuate and told a reporter that those who remained should write their name and social security number in felt pen on their arms, implying this would make it easier for emergency responders to identify their bodies.

Corpus Christi police said road debris and downed power lines were widespread and that an alleged intruder was taken to hospital after being shot by a homeowner. City officials advised residents to boil water. The city of Victoria, 30 miles inland, was also badly hit. Shelters were set up as far north as Dallas.

Harvey is the first major natural disaster of the Trump administration. Donald Trump’s proposed federal budget calls for a $667m cut to Fema funding, but the president was eager to give the impression he was ready for the challenge.

“Closely monitoring #HurricaneHarvey from Camp David. We are leaving nothing to chance. City, State and Federal Govs. working great together!” he tweeted on Saturday. A day earlier, Trump said he signed a disaster declaration to speed access to federal help.

The president’s attentiveness came after Chuck Grassley, a Republican senator from Iowa, warned him not to repeat the mistakes of George W Bush, whose inept response to Hurricane Katrina in 2005 came to define his presidency. Trump should “keep on top of hurricane Harvey”, Grassley tweeted, adding: “Dont mke same mistake Pres Bush made w Katrina.”

Trump responded that he had received Grassley’s message “loud and clear. We have fantastic people on the ground, got there long before #Harvey. So far, so good!”

Coastal areas remained vulnerable to storm surge, while the storm spawned several brief tornadoes in the Houston suburbs. One struck Sienna Plantation early on Saturday, ripping roofs at dozens of homes. After some neighbourhoods enjoyed a respite from the rains on Saturday afternoon, they returned to drench western areas in the evening, edging flood control reservoirs closer to their capacities and prompting more official warnings of potential flash floods and tornadoes.

One conservation group, meanwhile, warned residents to leave some displaced residents alone.

“Alligators can not stay in fast moving floodwaters for long and seek slow water to ride out the storm,” The Gator Squad said in a statement. “If you see a gator during the storm, as long as its not in a road or knocking on your door leave it be until the storm passes.”

Source: theguardian.com